Participants: Don Mackintosh (Host), Victor E. Herry
Series Code: HFAL
Program Code: HFAL000194
00:01 The following program presents principles designed
00:03 to promote good health and is not intended to take 00:06 the place of personalized professional care. 00:09 The opinions and ideas expressed 00:10 are those of the speaker. 00:12 Viewers are encouraged to draw their own 00:14 conclusions about the information presented. 00:49 Welcome to Health For A Lifetime. 00:50 We're glad you joined us today. 00:51 Our program today is about asthma and asthma impacts 00:55 many people with their breathing. 00:57 Talking with us today about this is Dr. Victor Herry. 01:00 He is a specialist in internal medicine. 01:03 Before he took that residency he did, 01:05 had training in allergies and the immune system 01:08 which is of course directly related to asthma, 01:10 isn't it doctor? That's correct. 01:12 We're glad today we're gonna talk about this 01:14 and hopefully you can increase our breath, 01:17 our breathing help people may be you know, 01:19 avoid this or I don't know. 01:21 We're gonna learn a lot of things 01:22 I'm sure from you today. 01:23 First of all we wanna learn what is asthma? 01:26 What's our working definition? What's asthma? 01:29 Asthma is the inability to breath well resulting 01:35 from two things, one inflammation 01:38 in the lungs and spasms in the lungs. 01:43 So that what happens in that case is the patient 01:46 who does have the disease has difficulty in breathing 01:51 and unable to catch his breath. 01:53 It manifests itself in different ways. 01:55 It might manifest as a cough, as chest tightness. 01:59 It might manifest itself an audible 02:02 wheezing or shortness of breath. 02:05 So you've talked also-- So the component, 02:07 the two main components are inflammation 02:10 and we cannot forget that because that's the most 02:13 important part of its treatment. 02:15 And the other part is spasms where the tiny muscles 02:21 of the bronchial tree go into tremors 02:24 as a result of the environmental changes. 02:28 So those two things and then you started to hint 02:30 to what the symptoms are of course 02:32 shortness of breath, what else? 02:34 Cough, shortness of breath, cough, audible wheezing, 02:38 tightness in the chest, any of those things 02:41 may be manifestations of asthma. 02:43 So going back to your first point then 02:45 the definition was of course some kind 02:48 of process inflammatory process--It's the process 02:51 in the lung that is--that consists of inflammation 02:56 and at the same time hyper responsiveness of the lung 03:01 and we say hyper responsiveness because 03:04 the tiny muscles, the smooth muscles 03:09 in the lung tree grow into the spasms and prevent 03:13 the person from breathing freely, 03:15 so that not enough air is going in 03:17 and not enough air is going out. 03:19 So that would be the causes of asthma. 03:21 The real cause or we're talking about causes 03:24 that's different than this, isn't it? 03:26 Well, that's what it is. 03:27 The cause can be, can vary from the environment. 03:31 For instance there are people 03:32 who have allergies and allergy may be a cause, 03:36 a precipitating factor, so that things 03:39 in your environment bothers you. 03:40 First of all you begin by sneezing and then wheezing. 03:44 See what happens in the lung there're some cells, 03:47 there're some mast cells or some T cells 03:52 which tend to break up. 03:54 When these cells break up they release substances 03:56 into the body and these substances into the body 04:00 that they release cause the inflammation 04:03 and in addition to causing inflammation 04:05 they cause the spasm. 04:07 So that's the simple physiology, 04:10 so that when the air goes in, the person, 04:14 the air is going in but the person can't 04:16 breath properly and what happens 04:18 is that the air way constricts. 04:22 So the normal air gets smaller and smaller 04:25 and the person has difficulty breathing. 04:27 Probably one of the most alarming things 04:29 that can happen to someone. 04:30 It does and there is an increase 04:32 in asthma and the increase happens in areas 04:36 of high pollution because we find that the presence 04:39 of pollution in the air sulphur dioxide 04:41 and carbon dioxide. Those act as irritants. 04:46 People who work in dusty areas 04:48 and may have some predisposition 04:50 to the problem. 04:51 We find that they end up having those problems. 04:54 Now there's the asthma resulting from allergies 04:58 especially in the spring when the flowers come up 05:00 and the tree pollens come up. 05:03 Now those things are inhaled and as they enter 05:06 the system the body tries to fight it. 05:10 Very interestingly and the body's trying to fight it, 05:13 the body produces substances 05:15 that are deleterious to the body itself. 05:17 So in other words this is really it's healthy 05:19 in one sense because the body's saying wait 05:21 this is a toxin let's not, let's get rid of it 05:24 but then it gets as too much of the good thing. 05:27 That's right and so what happens it overwhelms the body, 05:30 because the antihistamine mast. 05:32 These are protective cells that we have called mast cells 05:36 and these mast cells when they split up, 05:39 they release histamines and the histamine 05:42 and other substances that are released 05:44 by these cells cause the problem that we see. 05:48 You've already kind of answered these questions 05:49 but talking about who can develop asthma. 05:51 Of course someone in the polluted area, 05:53 someone in an area where there's lots of pollens 05:55 and these different things you've mentioned 05:57 but are there other people that are prone. 05:58 Predisposition. Yeah, what is that? 05:59 Now if there--if there's a family history 06:02 and it goes back to the family chief, 06:04 there is a family history of asthma. 06:06 Then one must consider if you have a son for instance 06:09 if you're an asthmatic or your grandmother 06:10 was an asthmatic and your son starts coughing every night. 06:13 It's not just simple, a simple cough you must explore 06:17 whether or not that child has asthma. 06:19 And one of the things that happens is that asthma 06:24 tends to occur primarily into the, 06:27 may be in the early morning hours when you notice 06:30 that your child is just coughing every night. 06:32 So parents will bring their children and say, John, 06:34 coughs every morning around 2 or 3 o'clock, 06:37 coughing all the time and that's an indication, that's asthma. 06:42 Now why early in the morning? Yeah, why is that? 06:44 Now the reason is that based upon the body circadian rhythm. 06:49 The cortisol level of the body drops early in the morning. 06:53 And the cortisol is a treatment for-- 06:55 And the cortisol is a treatment for asthma 06:56 because the body produces it's own cortisol. 06:58 Okay. And helps you 07:00 to overcome those kinds of things, 07:02 but when the level drops people who have predisposition 07:05 to the disease and have irritants may be dust mites 07:11 in the house where there's dust. 07:13 So the, the internal pollution by internal I mean 07:16 in the house pollution molds, dust, dust mites 07:21 those are things on the inside that people who have asthma 07:24 need to be very careful about and on--I'm sorry. 07:27 Excuse me. What about a person that has like eczema 07:30 or other types of allergy type things. 07:32 Are they more predisposed to asthma? 07:34 Yes, there're certain percentage of people 07:36 who have eczema and eczema is a skin allergy. 07:40 So certain percentage of people who do have eczema have asthma. 07:43 That's because they're susceptible to allergies. 07:46 And it's I guess a higher percentage. 07:49 A higher percentage than the normal population. 07:51 So the people that are at risk or who can develop asthma 07:55 are those with the family history, 07:57 those in the right in or right or shall we say 07:59 wrong environment and those that are anything else. 08:06 Yeah, now I want to make this one point 08:08 as I'm answering your question. 08:10 Now asthma manifests itself as wheezing. 08:13 Okay. But all wheezing is not asthma. 08:15 Okay. And the reason I'm saying 08:17 that is because the story is told of little boy 08:20 who was wheezing and his parents thought that he has asthma, 08:24 only to find out when he went to the doctor 08:26 even though they gave him medication. 08:28 He continued to wheeze because a small object 08:31 went into his lung and that caused the wheezing. 08:34 So all wheezing is not necessarily asthma. 08:38 That's why they got a chest x-ray. 08:39 That's why they got a chest x-ray 08:40 and they did a chest x-ray on that kid 08:42 and as a result found that object in there. 08:46 So we talked about the causes and who can develop it. 08:49 What are some risk factors or is that already 08:51 been covered in what we talked about. 08:52 Well, the risk factors we talk about that people 08:56 who are predisposed, people who have allergies. 08:58 If you have allergies, it means that you should 09:01 have your allergies treated because 09:03 there's a continuum between allergy and asthma. 09:08 So we've found that kids who have allergies 09:11 may move on to develop asthma 09:13 if the allergies are not taken care of. 09:15 So if you see kid that has eczema 09:20 or other allergies of any kind. Right. 09:22 They don't get better, they sometimes can get worse 09:25 and one of the things is asthma. 09:27 That's right, that kid should be taken to his physician, 09:30 his or her physician, so that steps could be taken 09:34 to reduce the possibility, because the irritants 09:37 on the outside that causes the allergic response. 09:42 Remember that asthma also is an allergic response 09:46 and as the body response to that offending allergen 09:51 and I use a word offending because it causes 09:53 a negative response in the body. 09:56 So with the pollens of the air pollens, 09:58 the grass pollen, the tree pollen, 10:01 the dust in the house, the molds, leaking roofs, 10:05 any of those kinds of things that you have 10:08 in your household that should be gotten rid off, 10:10 because they can predispose a person 10:13 to having, to develop an asthma. 10:16 So why would a leaky house do that? 10:18 The mold, molds spores grow, yeah. 10:21 I see. And by inhaling those spores 10:24 it irritates causes the inflammatory process 10:28 and then the response to that would be wheezing or asthma. 10:32 I mean it's fascinating to hear that as nurse 10:34 and also a minister, because you know, 10:35 in Old Testament they have a whole chapter 10:37 about sick houses and they get so sick sometimes they say, 10:40 ye they have this much and it knock it over 10:43 and he was allergist, God is an allergist too. 10:47 So what are the affects of asthma on your body? 10:52 Now, I'm glad you asked that question 10:55 because for children it affects their concentration. 11:01 So that's one of the, the other thing 11:04 is certainly it can result in death because 11:07 the death rate of asthma is increasing 11:10 because people take it so lightly. 11:13 Okay, so those who have allergies need to make sure 11:17 that the allergies are taken care 11:20 of to prevent the continuum into asthma. 11:23 So allergies can lead to asthma, asthma can lead to death. 11:28 Asthma can lead to behavior problems 11:32 because the child who has asthma all the time 11:35 he can't concentrate and a result of that 11:40 he manifest bad behavior because of his 11:43 inability to concentrate and he's pushed aside. 11:48 So he starts to have act out as a result. 11:50 Act out as a result. 11:51 So how does it really work that he can't concentrate, 11:54 because he is wheezing, he's doing this, 11:56 he's doing that, or he's because 11:57 the oxygen level is low in his brain or what? 12:00 You've raised a good point because the presence of asthma, 12:06 active asthma in the system reduces the oxygen level. 12:10 It certainly does because that's the whole thing 12:12 when you're wheezing you're not getting enough air, 12:14 you're not getting enough oxygen 12:16 and because you're not getting enough oxygen 12:18 it's been choked off your brain 12:20 therefore it's not at its maximum. 12:22 So you can result in death. 12:25 Right, so the concentration goes down and there's an 12:28 increase in irritability because of that and so it's not, 12:32 you don't spank the child, you say wait a minute 12:34 there must be something more. 12:35 That's right, that's right. 12:37 Okay, now you keep bringing up death 12:39 going from concentration to death. 12:41 I mean I know there's an intermediate stage, 12:43 but the reason you do that is because there can just be 12:45 sudden death from some, you know, 12:48 an asthma attack, I'm sure you've-- 12:49 That's right. The reason I bring death 12:51 because that's the ultimate and because the death rate 12:54 of asthma in the United States is increasing. 12:57 Even though we have medications 13:01 that can treat the disease, okay. 13:03 So it means then that we are not paying enough attention 13:07 and so we need to pay more attention to the asthmatic, 13:11 to the children who may be a child who has asthma 13:14 may be extremely quiet one day 13:15 and you wonder why the child is quiet. 13:17 The child may not be able to breath properly, 13:19 but he's just been quiet because of the inability to breath. 13:22 I see. Okay. 13:23 And so we must pay attention. 13:25 Are there population or ethnic groups 13:28 that are most acceptable to asthma than others? 13:30 What we do find this in that the central cities, 13:36 asthma is increasing in the central cities, 13:38 and those populations who live in the central cities 13:41 in Los Angeles, in Washington D.C. 13:43 Baltimore, Maryland. 13:45 We find there's an higher incidence of asthma 13:48 and the factors are many, number one pollution. 13:52 Right, in the city area. In the city area, you know, 13:54 the cars, the carbon monoxide, 13:56 the carbon dioxide, all of those things. 13:58 Secondly the housing nature of those in the cities, 14:04 how it acts, because of the poor housing you have irritants, 14:10 I've mentioned molds earlier on, 14:12 cockroaches that can cause asthma. 14:15 Is that right? That's right. 14:16 So if your house is infested with cockroaches, 14:19 then you need to get rid of it because that can cause asthma. 14:22 So we found that mites which was in the dust, 14:25 dust mites, cockroaches, those are thing that you find 14:31 in particularly in the city places 14:34 or places that are not well kept. 14:36 We're talking with Dr. Victor Herry. 14:38 We're talking about asthma 14:39 and we're learning some very interesting things. 14:41 We're starting to get a hint that though it's a bad problem, 14:44 there're some things you can do to, you know, 14:47 slow it down, perhaps stop it. 14:49 We're gonna talk about how you can prevent it perhaps treat it, 14:53 control it, turn it around when we come back. 14:57 Are you confused about the endless stream of new and often 15:00 contradictory health information. 15:03 With company's trying to sell new drugs 15:05 and special interest groups came for study this spin effect, 15:09 where can you find a commonsense approach to health. 15:12 One way is to ask for your free copy of Dr. Arnott's 15:15 "24 Realistic Ways To Improve Your Health." 15:18 Dr. Timothy Arnott and the Lifestyle Center of America 15:21 produce this helpful booklet of 24 short practical health tips 15:24 based on scientific research and the Bible that you help you 15:28 live longer, happier, and healthier. 15:30 For example did you know the women who drink more water 15:33 lower the risk of heart attack or the 7 to 8 hours of sleep 15:37 in night can minimize your risk of ever developing diabetes. 15:41 Find out how to low your blood pressure and much more. 15:44 If you're looking for help not hide them 15:45 this booklet is for you. 15:47 Just log on to 3abn.org and click on free offers 15:50 or call us during regular business hours, 15:53 you'll be glad you did. 15:56 Welcome back. We've been talking with Dr. Victor Herry. 15:59 Dr. Herry is a specialist in internal medicine. 16:02 Before he did that residency however he did study 16:05 in allergies and the immune system 16:08 which is directly related to asthma 16:10 as we saw in the first half of our program. 16:12 We saw that this is a huge problem in America 16:15 and you said it's only increasing. 16:17 Yes. People don't take it seriously enough. 16:19 They don't recognize the connection between 16:21 the allergic system or allergies and how it can lead onto asthma 16:26 and you really have a burden for this and rightly so. 16:28 You live in inner city, you talk with people 16:31 that are in poor houses and all these different things 16:33 we talked about in the first half. 16:35 We wanna talk about detecting asthma 16:39 and then perhaps treating it, turning it around 16:41 and what types of thing we can do. 16:43 You've hinted some of these things to us focusing on it. 16:46 Now how do you detect it? 16:49 Now talking to the parent if you notice that your child has 16:56 some difficulty in breathing or if you notice that 17:00 your child has shortness of breath or if you perhaps notice 17:04 that your child may have excessive runny nose, 17:07 take the child to the doctor, that's the first thing. 17:10 Now the doctor then makes the diagnosis by doing 17:13 a special test call pulmonary function test 17:16 that is with the doctor ask to have that child breath 17:21 into a machine and then based upon the breathing test, 17:26 the doctor can determine certainly that this child 17:29 or this person or this adult has asthma. 17:33 Now we talked earlier on of the components. 17:36 Now in the two components that I mentioned earlier, 17:39 one is the inflammatory component and the other one 17:42 is the irritable component, 17:44 there are the hyper irritability component 17:46 which with the muscle fibers just going to spasms. 17:50 It is an important to note that in treatment in today, 17:54 we have found out that the most important component, 17:58 both components are important. 17:59 But the most important one is the inflammatory component 18:03 and so in the treatment of asthma one uses 18:07 corticosteroids as the main stay of the treatment 18:09 of asthma today, because it takes care 18:12 of the inflammatory component of the disease. 18:15 Is there any down side to taking corticosteroids? 18:19 Generally speaking no. There is a down side if you take 18:23 high dosage for long periods of time, 18:26 but at the low dosage and which those steroids 18:31 are inhaled they're virtually no down side. 18:34 Studies have been done on the growth of children 18:37 and we find that in taking 18:39 the appropriate amount they grow normally. 18:42 Suddenly if you have to use high dosage over long periods 18:44 of time that can affect the growth 18:46 in children or in adults who have very bad asthma. 18:51 They can develop as part of the secondary cause 18:54 of using high corticosteroids. 18:56 You can develop cataracts. 18:58 You can develop diabetes as a result of 19:01 taking high dosage of corticosteroids. 19:04 You can develop hypertension because corticosteroids 19:06 tend to increase blood volume. 19:09 But we're talking about the extreme here. 19:12 Right. That's very, very high dosage 19:14 but on the normal circumstances no. 19:17 Okay, so the detection we've talked about that. 19:19 Now, you know, some people are very interested 19:21 in plant sterols when they have their kids 19:24 that are have access to more different things. 19:26 There's a lot of these substance you can buy 19:27 in this health food stores and what not. 19:31 My feeling is that you need to go to a trained, 19:34 professional and then get it checked out. 19:37 How do you feel about this? That's very important. 19:40 Go to the trained professional have it evaluated 19:44 and diagnosed and treat it, 19:47 because it is too serious a disease to play around with. 19:50 So the treatment then you've alluded 19:52 to can be the you know, steroids. 19:54 I've mentioned one of the treatments 19:56 and that is the use of inhale corticosteroids 19:59 and the other is the use of some beta genetic agents 20:05 which are use in inhalers 20:08 and that is more further rapid response. 20:13 So if a person is wheezing you need a rapid response 20:16 and in times pass you give an injection of adrenaline. 20:19 Now we have other substances 20:21 that you can use and inhale them. 20:24 You can use a metered dose inhaler 20:26 or you can use through a nebulizer that's a little cup 20:31 in which you put the medication 20:33 and the person inhales that back and forth. 20:35 So those are things that we can do to treat 20:37 the disease in the active state. 20:40 And in that active stage, lets say you're up on 20:42 the mountain and you don't have 20:44 your medicine with you, what you do then? 20:46 Oh, you better have your metered dose inhaler, 20:48 but I understand that in some cases people are told that 20:54 if one has an acute wheezing process, 20:58 they can use the Heimlich maneuver to enable 21:00 that person to breath better, 21:02 but I have not started that to a large extend. 21:06 But I understand that's, that's one of the things 21:07 that could be done, but get down the mountain 21:10 as fast as you can, get yourself to a doctor. 21:14 And if your child has asthma and he or she is going on a camp 21:19 or an outing be sure that you have the medication. 21:22 You know, sometimes you know, you've got the inhaler, 21:24 is there any oral medication people take that, 21:28 you know, to deal with this. 21:29 There are oral medications that can be used for it, 21:32 but we're moving, we tend to be moving away 21:36 from oral medications more to the inhale, 21:39 because what happens with the inhalers, 21:41 you provide the medication directly at the point of need. 21:45 I see. By taking a lot of 21:47 oral medications what happens and we still use 21:50 oral medications, but those are oral medications 21:53 that you systemically and we are moving away from that now. 21:57 Is that right? So they don't, 21:58 they don't check their blood levels and all that stuff- 22:00 No those things, those things are- 22:02 We're moving away from them. Yes, we are. 22:04 Now what about then, I mean we've done 22:06 a lot of education in this program, 22:08 but what additional things do you tell 22:10 your patients when they come? 22:12 Now one of the things that we need to keep in mind 22:16 is that the environment must be clean 22:18 and so a dusty environment to an asthmatic 22:22 is a gun to a person's head. 22:25 So which means that the environment 22:27 must be free of dust, free of inhalants, 22:31 right free of molds, we talked about 22:32 molds spores and how they act as irritants. 22:35 Cats? And pets in some cases, 22:38 it's very hard to get rid of pets, 22:41 but one of the things that we do today 22:43 is that we skin test that person for allergy to the pets 22:48 be the dog or cat and then provide immunotherapy. 22:51 If that child or that adult 22:53 doesn't want to part with that pet. 22:57 So we try to give him immunotherapy to that person 23:00 hopefully that they can overcome 23:04 the offending nature of the allergy to the pet. 23:07 So you know, allergy testing I mean 23:09 they have hundreds or thousands of things you can test for. 23:12 Do you run those kind of things in your office? 23:14 Yes, but what happens is depending on. 23:17 If you're dealing with internal in house allergies 23:21 as oppose to out, allergies on the outside. 23:25 I see. So you can test for pollens 23:26 in different regions of the country or of the world 23:29 you test for different things. 23:31 So the trees that grow up in Northern Canada 23:33 are not the same trees that grow in Florida 23:36 or the trees that grow here in Southern Illinois 23:38 and now the same thing that may grow in California. 23:40 So you test for things in your environment. 23:43 What's the best place to live in America if you're an asthmatic? 23:47 Wherever you can live. 23:49 So you just have to test this out. 23:51 Some people move to Arizona for instance 23:54 because they have asthma when they are in 23:55 the Northeast or some place else. 23:57 But sooner or later because they have that 24:00 predisposition to allergies, sooner or later they develop 24:03 the allergies in the area that they moved to. 24:05 So in another words, you can run but you can't hide. 24:12 You know, you practice lifestyle medicine, 24:16 I mean you're board certified internal medicine, 24:18 you practiced with a group of physicians 24:20 there in the D.C. area. 24:23 But you always try to address things 24:25 through lifestyle type things, changes. 24:28 And a lot of these things had to do with that, 24:31 I mean looking at your environment, your housing, 24:33 looking at the different things you come in contact with, 24:36 treating allergies you've talked about. 24:38 Any other lifestyle type things that you would say 24:42 in a general sense than more specifically with asthma? 24:45 It's important to, not to change activities. 24:49 In other words, a person who is asthmatic should exercise. 24:52 Okay. There should be no reason 24:54 why the person should not exercise. 24:56 And also there's exercise induced asthma 24:59 and people who are prone to that. 25:00 But these people can take the medication before the exercise, 25:04 so that during the exercise they do not get the asthma attack. 25:07 So don't stop exercising, but make sure 25:10 you're equipped for the exercise. 25:11 That's correct. And what else? 25:13 So exercise, take care of you environment, 25:16 remove any offending agents in your house and eat properly. 25:21 It's important to eat properly too, 25:22 because there's somethings that do predispose. 25:25 I think earlier on we might have spoken about the ability 25:30 of white blood cells to phagocytes 25:34 or to carry out its function. Okay. 25:37 And you know, if you eat certain diets 25:40 that prevent white cells from carrying out its function, 25:43 that predisposes you to other things. 25:47 Now why am I mentioning that with the asthma, 25:49 because in the case of asthma you need white blood cells too 25:54 and those white blood cells do release 25:57 certain substances that may cause problems. 26:00 Okay. So diet is important even in this. 26:03 All right, what about fluids? 26:05 You must drink a lot of fluids. 26:07 It's always important to drink a lot of water. 26:11 Water because water keeps your body hydrated. 26:14 The person who is asthmatic, 26:16 the person who is wheezing loses a lot of water. 26:20 Remember just from regular respiration we lose 26:23 approximately 600 cc of water which is about two eight ounces 26:27 glass of water, two and half eight ounces 26:29 of glass of water just from ordinary respiration. 26:32 Imagine if you're breathing faster 26:34 as if you're running so you need to be in hydrated. 26:38 What about anxiety as it relates to asthma anything about that? 26:42 Stress, now that's one of the things that can. 26:46 As a matter of fact I was reading recently about 26:50 the effect of stress on children who are asthmatics 26:55 or on anybody for that matter, so that can create anxiety. 26:59 So as much as possible relieve the stress sores. 27:04 Get rid of those so that your life 27:08 can be healthier and you can breath better. 27:12 Dr. Herry, we're delighted that you could spend time with us 27:15 at 3ABN and do this program on asthma 27:18 as well as the others you've done with us. 27:20 And this has been very meaningful work. 27:23 We wanna give our special thanks also to your wife, 27:26 the other physicians there that allowed you 27:27 to have the time off. 27:28 We're glad you could join us. Thank you for calling me. 27:30 And we're grateful that you could join us 27:32 as well today for this important program. 27:34 We've learnt a lot today about breath 27:37 and as it relates to asthma you know underneath 27:42 all this are thankful to God who gives us the ability to breath 27:46 to begin with and has set us up to learn about Him through that. 27:50 We're really dependent for every breath 27:52 on our Maker and our King. 27:54 And we hope today as a result of this program, 27:56 you have many more breaths and can serve the Master. |
Revised 2014-12-17