A new infrared tympanic thermometer in surgery and anesthesia

We have evaluated a new infrared tympanic thermometer, IT-10, as an intraoperative temperature monitor in patients with or without open abdominal surgery. It determines temperature by measuring infrared radiation given off by a warm object. Temperatures measured with this device were closely correlated with those measured with rectal and bladder thermometries. We conclude that this new tympanic thermometer is safe, convenient, accurate, and easily usable in the clinical situation.

The difference between Japan and other countries, in particular the United Kingdom, in views regarding the teaching of geriatrics to undergraduate medical students

OBJECTIVES

To examine differences in views on geriatrics education at the undergraduate level between Japan and other industrialized countries, including the United Kingdom.

DESIGN

We conducted a nationwide survey of professorial staff responsible for undergraduate education in all medical schools in Japan, and an international survey of 37 medical schools and geriatric institutes in other industrialized countries, including 16 medical schools in the United Kingdom.

RESULTS

The results indicate that undergraduate education in geriatrics in Japan emphasizes the theoretical aspects of the aging process and the features of diseases in the elderly, and lacks attention to the practical aspects of care. In contrast, geriatrics education in the United Kingdom and other countries places emphasis on practical aspects of the care of the elderly.

CONCLUSIONS

The introduction of practical aspects of management and care of the elderly to the undergraduate education programme in geriatrics in each medical school in Japan is strongly recommended. This is especially important to meet the needs of the rapid demographic shift towards an older population in this country.

Brain angiotensin II tonically modulates sympathetic baroreflex in rabbit ventrolateral medulla

The role of endogenous angiotensin II (ANG II) at the level of the rostral (RVLM) and caudal ventrolateral medulla (CVLM) in the control of sympathetic baroreflex function was investigated in urethan-anesthetized rabbits. The baroreflex relationship between mean arterial pressure and integrated renal sympathetic nerve activity (RSNA) was compared before and during microinfusion of saralasin, an ANG II receptor antagonist into RVLM or CVLM. The infusion of saralasin (20 pmol/min) into RVLM reduced the upper plateau, the range, and the range-dependent gain of the baroreflex, as well as the resting level of RSNA. The infusion of saralasin into CVLM augmented the upper plateau, the reflex range, and the range-dependent gain, whereas it did not alter the resting level of RSNA or mean arterial pressure. These results suggest that 1) the ANG II networks in RVLM are tonically active, influencing the resting level of the sympathetic outflow and facilitating the sympathetic baroreflex function, and 2) the ANG II networks in CVLM do not significantly influence the sympathetic activity in the resting state but exert an inhibitory effect on the baroreflex response when arterial pressure falls below the resting level.

[University education in geriatrics--present status and future prospects of gerontology and geriatrics education in pathology]

The increase in the number and proportion of the elderly in Japan over the last 30 years has been faster than that in any other country. One of the measures we are compelled to take to deal with this drastic change in medicosocial circumstances is reform of the medical school curriculum. However, the necessary reforms are being implemented slowly and are still insufficient. We surveyed the present status of gerontology and geriatrics education in pathology, and the understanding, interest, and opinions on this matter among professors of pathology. Questionnaires were sent to 148 professors of pathology in 80 medical schools. Responses were received from 84 professors (57%) at 64 medical schools (80%). Of the 11 medical schools with a department of geriatrics 10(90%) included gerontology in the curriculum. In contrast, 43(80%) of the 53 remaining schools did not include gerontology in the curriculum, although education in geriatrics and gerontology has been given as part of pathology lectures in almost all medical schools. Many professors want to establish a department of geriatrics in their school, but feel it will be difficult because of lack of money and higher priority given to other fields. As other hindrances, most of the respondents noted the lack of money and higher priority given to other fields. As other hindrances, most of the respondents noted the lack of a good textbook of gerontology, ambiguity in the concept of the field, and the immaturity of gerontology as a science. Another major problem noted was uncertainty regarding the status of geriatrics as a clinical specialty. One professor mentioned that promotion of aging research would be the best way to solve these problems.

[Undergraduate teaching of geriatric medicine in western countries--literature review]

To help plan for the future of undergraduate education in geriatric medicine in Japan, we reviewed the literature concerning undergraduate teaching of geriatric medicine in western countries. Undergraduate teaching in geriatric medicine in the UK is well developed: 22 of 25 universities have a full department of geriatric medicine. Training in geriatric medicine is mandatory in almost all universities. In contrast, geriatric medicine is an elective in most universities in the US. There is a shortage of geriatric medicine faculty in the US, which is similar to the situation in Japan. Clinical and basic research in geriatric medicine and gerontology should be encouraged to attract persons into this field.

[University education in geriatrics: medical students' understandings of gerontology and geriatric medicine]

With the rapid aging of Japan's population, medical professionals who specialize in geriatric medicine are in unprecedented demand. To meet that demand and to improve the curriculum for teaching geriatric medicine and gerontology in Japan, we surveyed medical students' understandings of these specialties. Students at 14 schools with classes in geriatric medicine and gerontology were surveyed. A questionnaire was sent to sixth-year medical students after their classes had ended. Questionnaires were collected from 849 students (60.1%) at ten medical schools (74.1%). One quarter (24.5%) of the students were satisfied with the contents of the classes in geriatric medicine and gerontology taught in their school, whereas 39.4% were not. These specialties encompass many fields of clinical and basic medicine, and many students found the lectures difficult to understand (41.4%). Inter-school comparisons of the results showed that students' strengths and weaknesses in the various areas of geriatric medicine reflected differences in the contents of the classes among the schools. Only 35.4% of students had ever visited hospitals or other health-related facilities for the elderly. Many students (58.8%) had never lived with elderly people. Most students (63.9%) wanted visits to health-care facilities for the elderly to be included in their regular curriculum. Medical students are conscious of the medical implications of the ageing of Japan's population; 13.2% had volunteered to work with the elderly.

[University education in geriatrics: medical student's opinions on gerontology and geriatric medicine]

With the aging of Japan's population, physicians need to be aware of advances in geriatric medicine. To assess the status of geriatric medicine in undergraduate education, we surveyed of medical student's opinions on gerontology and geriatric medicine. A questionnaire was sent to six-year medical students at a total of 20 schools that did not include geriatric medicine in their curriculum. Responses were obtained from 950 students (47.6%) at 16 schools (80%). Almost half of the students (42%) had experiences in health care facilities for the elderly. Ten percent were content with their education in geriatric medicine education and 59% were not. A total of 41.4% felt that geriatric medicine is difficult because it involves many different subjects. Some students had experience as volunteers working with elderly people; they were aware of the aging of Japan's population, and felt that their training in basic geriatrics and in geriatric diseases was insufficient. A total of 56% agreed that all medical schools should have classes in geriatric medicine and 14% did not. Medical students in the schools without classes in geriatric medicine identified dementia (73%), cerebral vascular accidents (51%), cancer (24%) and osteoporosis (19%) as common in elderly people, with no differences between schools. The corresponding data for medical students in schools with classes in geriatric medicine were dementia (77%), cerebral vascular accidents (44%), osteoporosis (29%), and cancer (16%). Undergraduate medical students seem to be exposed to widely differing curricula with regard to geriatric medicine. We found a lack of uniformity in the teaching of gerontology and geriatric medicine to undergraduate medical students in Japan.

[University education in geriatrics. Opinions of teaching staff on undergraduate education in gerontology and geriatric medicine]

Undergraduate education in gerontology and geriatric medicine has become more important because of a progressive increase in the aged population. To assess curricula in geriatric medicine and to survey the opinions of teaching staffs as to the ideal curriculum, a questionnaire was sent to professors of gerontology and geriatric medicine at 14 medical schools. Responses were obtained from all 14 professors. In all medical schools, students are given lectures in the fifth or sixth year, or both. The total number of hours for the lectures varied from a few hours to 40 hours, and contents of the lectures varied between schools. Medical staffs pointed out that little time is allocated to geriatric medicine. They also emphasized the importance of bedside teaching.

[University education in geriatrics. Present status and future plans of universities regarding the development of a program in geriatrics]

Because the number of people who reach an advanced age has been increasing at an unprecedented rate in Japan, geriatricians are expected to play a central role in health care for the elderly. However, only 16 out of 80 medical schools (20 percent) now have departments of geriatrics for undergraduate education. To develop undergraduate education in the field of geriatrics, a survey was sponsored by the Research Projects on Aging and Health (Health Science Research Grant the Ministry of Health and Welfare of Japan). A questionnaire regarding the present status and future plans of the university about a program in geriatrics, was sent to deans of medical faculties or vice-presidents of medical schools. The questionnaire included questions about current status and future plans regarding undergraduate geriatric education, the presence of a department or clinic of geriatrics, educational requirements in the field of geriatrics, opportunities for practice, institutions of practice, research on geriatrics, and other suggestions. The response rate was 93.7 percent (74/79). Departments or clinics of geriatrics had been established in 15 institutions (20.3 percent) and were planned in 18 (24.3 percent). Undergraduate education in geriatrics was considered necessary in 73 schools (98.7 percent) and indispensable as an obligatory subject in 56 (75.7 percent). Clinical practice was considered more important and effective than lectures in 50 schools (63.3 percent). Coordinated lectures on basic biomedical gerontology (such as mechanism of aging) and geriatric medicine for chronic degenerative diseases such as senile dementia were considered essential to the curriculum. In practicing geriatrics, experience in providing medical care to aged patients as well as social support and a welfare system for the aged is emphasized. Institutions, nursing homes, and geriatric hospitals outside medical schools be easily accessible. It was generally agreed that geriatrics should be taught in advanced classes. In conclusion, medical schools in Japan regard undergraduate education in geriatrics as necessary and agree on the optimal curriculum, but it is not universally implemented.

Procaine microinjection into the lower midbrain increases brown fat and body temperatures in anesthetized rats

A tonic inhibitory mechanism on heat production was studied by microinjecting procaine into various regions of the brain while recording temperature changes of the interscapular brown adipose tissue (IBAT) and rectum in urethane-anesthetized rats at room temperature of 23-25 degrees C. Procaine microinjected bilaterally (10%, 1.0 mu l/site, 1.5 mm to midline) into the midbrain and the upper- to mid-pontine area of the reticular formation increased temperatures of the IBAT and rectum. The highest temperature rise (1.02 +/- 0.11 degrees C for IBAT, 0.64 +/- 0.06 degrees C for rectum) with the shortest onset latency (1.5 +/- 0.3 min for IBAT, 4.6 +/- 1.1 min for rectum) was observed when procaine was injected into the lower midbrain (the area between 6 and 7 mm posterior to the bregma, and 6.5 to 8.5 mm deep from the cortical surface). These regions include the retrorubral field, pedunculopontine tegmental nucleus, and rubrospinal tract. Procaine-induced IBAT and rectal temperature increases were dose-dependent, and reproduced reliably from the same injection site of the same animal. Intravenous indomethacin, a prostaglandin H synthase inhibitor, did not affect procaine-induced temperature rise, and propranolol, a beta-blocker, completely blocked it. These results suggest that microinjected procaine exerts its local anesthetic effect and release a tonic inhibition resulting in a disinhibition-induced temperature increase through the enhanced central sympathetic outflow. They support the hypothesis that a bilateral tonic inhibitory mechanism on heat production exists in the lower midbrain.

Usefulness of R-R interval and its variability in evaluation of thermal comfort

The use of R-R interval and the coefficient of variation in R-R intervals (CVR-R) for the evaluation of thermal comfort was investigated. The experiments were carried out with ten male subjects but data from one were excluded from the analysis. Thermal sensation, comfort, and tolerance of environmental conditions were reported and mean skin temperature, R-R interval and CVR-R were monitored during a 3 h period in a climatic chamber with the operative temperature set at 26, 20, or 30 degrees C. Relative humidity was maintained at ca. 50% in each case. At the operative temperature of 20 degrees C, the mean skin temperature was significantly lower, the cold sensation was significantly more intense, and discomfort was significantly greater than at 26 degrees C and R-R interval was increased significantly. Seven of the nine subjects were unable to tolerate this thermal environment. The R-R interval and CVR-R were increased in five and four of those seven subjects, respectively. At the operative temperature of 30 degrees C, the mean skin temperature was significantly higher, and the sensation of warmth was significantly more intense than at 26 degrees C. Seven of the nine subjects felt discomfort, and four of the seven reported an inability to tolerate this thermal environment. The R-R interval and CVR-R were decreased in four and three of these four subjects, respectively. At the operative temperature of 20 degrees C CVR-R was significantly greater than that at 30 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

What roles does the organum vasculosum laminae terminalis play in fever in rabbits?

Experiments were designed to clarify the role of the brain's organum vasculosum laminae terminalis (OVLT) in the development of fever in rabbits. Rectal and ear skin temperatures were recorded in conscious animals in which the OVLT had been electrolytically destroyed or in which the preoptic anterior hypothalamus (PO/AH) had been transected bilaterally. When the OVLT had been ablated the febrile responses to intravenous injection of interleukin-1 beta (IL-1 beta) or tumour necrosis factor alpha were significantly attenuated, while those to intracerebroventricular injection of IL-1 beta were not affected. Fever induced by intracerebroventricular injection of prostaglandin E2 (PGE2) was prolonged significantly. The febrile responses to intravenous injection of IL-1 beta and to intracerebroventricular injection of PGE2 were attenuated when the transection was located caudally to the anterior wall of the third ventricle and extended laterally more than about 3 mm in the ventricular wall. The results show that the OVLT region is a site through which signals to increase body temperature are transferred from the blood to the brain in rabbits.

Does interleukin-1 mediate tumour necrosis factor alpha-induced fever in rabbits?

We investigated the humoral mechanisms involved in tumour necrosis factor alpha (TNF alpha)-induced fever in rabbits. No change in lymphocyte-activating factor activity was detected in serum drawn during TNF alpha-induced fever. The pyrogenic activity of recombinant rabbit interleukin-1 beta (IL-1 beta) was entirely abolished by pre-incubation with anti-IL-1 beta antiserum from the goat. Fever induced by intravenous (i.v.) injection of IL-1 beta was significantly diminished by i.v. infusion of the antiserum. However, i.v. infusion of the antiserum for 1 h did not affect fever induced by i.v. injection of TNF alpha, when the antiserum infusion began either simultaneously with, or 2 h after, the injection of TNF alpha. Furthermore, intracerebroventricular injection of the anti-serum did not affect TNF alpha-induced fever. The intracerebroventricular administration of naloxone (an opioid receptor antagonist) significantly diminished TNF alpha-induced fever. The results suggest that IL-1, both in the blood circulation and in the brain, may not be involved in TNF alpha-induced fever. Similar to the contribution of eicosanoids, the opioid system in the brain seems somehow to contribute to the mechanism of the development of fever induced by TNF alpha in rabbits.

Intraperitoneal injection of 1-oleoyl-2-docosahexaenoyl phosphatidylcholine enhances discriminatory shock avoidance learning in rats

Effects of injection of 1-oleoyl-2-docosahexaenoyl-sn-glycero-3-phosphorylcholine (ODHPC) on learning ability were investigated in rats using discriminatory shock avoidance learning task. When ODHPC (2 mumol) was intraperitonealy administered 5 min before the beginning of the first trial of learning task from the second to fifth sessions, avoiding rates of the ODHPC-injected group were significantly higher than those of the control group. However, any injection of ODHPC derivatives, such as 1-oleoyl-2-docosahexaenoyl-diacylglycerol, 1,2-dioleoyl-sn-glycero-3-phosphorylcholine, glycerophosphorylcholine, docosahexaenoate, oleate and choline chloride, did not affect learning. These results suggest that intraperitoneal ODHPC injection enhances learning ability by its specific conformation.

1-Oleoyl-2-docosahexaenoyl phosphatidylcholine increased paradoxical sleep in F344 rats

The effects of administration of 1-oleoyl-2-docosahexaenoyl-sn-glycero-3-phosphorylcholine (O-DH-PC), a kind of lecithin, and of glycerophosphorylcholine (GPC) on sleep were investigated in male F344 rats. Intracerebroventricular administration of O-DH-PC at a dose of 10 micrograms/rat induced significant increase in paradoxical sleep time and total sleep time in the following 24 h, while administration of GPC did not. Results suggest that O-DH-PC affects on neuronal mechanism relating to paradoxical sleep, and that the effect of O-DH-PC might be caused by fatty acid residues, rather than choline residue.

Comparison of TRH and its analog (NS-3) in thermoregulatory and cardiovascular effects

The effects of TRH and its metabolically stable analog NS-3 [(3R,6R)-6-methyl-5-oxo-3-thiomorpholinylcarbonyl-L-histidyl-L-pro linamide tetrahydrate] on thermoregulation and circulatory control have been investigated. Both NS-3 (1-100 ng/kg ICV) and TRH (0.1-10 micrograms/kg ICV) increased rectal temperature and metabolic rate with a transient cutaneous vasoconstriction in conscious rabbits. They also increased arterial blood pressure, heart rate, respiratory rate, and renal sympathetic nerve activity (RSNA) in urethane-anesthetized rabbits. Ten ng/kg of NS-3 and 10 micrograms/kg of TRH had comparable hyperthermic, pressor, and tachycardic activities, while the relative potency of NS-3 to increase RSNA was greater and that to increase metabolic rate was smaller than the other effects. In conclusion, NS-3 was more potent than TRH in all of the effects measured, but there was a dissociation in the relative potency of NS-3 in the different autonomic effects.

[Effect of halothane on the peripheral cutaneous vasoconstriction and shivering induced by internal body cooling in rabbits]

Although suppression of thermoregulatory mechanisms by anesthetics is generally assumed, the extent to which thermoregulatory responses are active during general anesthesia is not known. To evaluate the effect of anesthetics on thermoregulation, we investigated the threshold body core temperatures to induce peripheral cutaneous vasoconstriction and shivering in spontaneously breathing rabbits. Rabbits are anesthetized with halothane at 0.05, 0.2 and 0.4 MAC (minimum alveolar concentration). Internal whole body cooling was performed by perfusing the cool water through an intestinal U-shaped thermode placed in the colon. Core (esophagus) and peripheral (ear) temperatures were measured with thermistors. The esophageal temperatures at the beginning of peripheral cutaneous vasoconstriction and shivering induced by internal whole body cooling were determined. Peripheral cutaneous vasoconstriction was not significantly affected by halothane. However, the incidence of shivering was significantly decreased by halothane dose-dependently. Threshold of shivering (37.3 +/- 0.8 degrees C) was significantly lower than that of peripheral cutaneous vasoconstriction (38.9 +/- 1.1 degrees C). We conclude that the halothane can exert an influence on shivering.

Hypothermia enhances contractile responses of the guinea pig taenia caeci to acetylcholine, 5-hydroxytryptamine, caffeine and calcium

Isometric contraction of isolated guinea-pig taenia caeci was induced with acetylcholine (ACh) and 5-hydroxytryptamine (5-HT) at 37 and 30 degrees C to investigate the effect of hypothermia on the response of smooth muscle to neurotransmitters. Lowering the temperature increased the amplitude of contraction in response to 10(-6) M ACh. Contraction in response to 10(-6) M 5-HT was also greater at 30 degrees C. 5-HT-contraction was not inhibited by atropine, but was inhibited by ketanserin. Calcium-contraction was also induced in an isosmotic high potassium solution. The amplitude of the contraction elicited by 5 x 10(-3) M Ca was significantly greater at 30 degrees C, and was inhibited by verapamil. The amplitude of the contractile response to 5 x 10(-3) M caffeine was also greater at 30 degrees C than at 37 degrees C. The finding that both calcium- and caffeine-contraction were enhanced at low temperature raises the possibility that intracellular calcium participate in cold-induced enhancement of contraction.

Action site of circulating interleukin-1 on the rabbit brain

Interleukin-1 (IL-1) is now generally accepted as an endogenous pyrogenic mediator of fever induction. IL-1 induces fever by means of activation of arachidonate metabolism in the brain. However, whether circulating IL-1 enters the brain or not, further, the question of where is the action site of circulating IL-1 on the brain, have not been clearly demonstrated. In the present study, to investigate the site of action of circulating IL-1 on the brain, recombinant rabbit interleukin-1 beta (IL-1 beta) was labeled with colloidal gold, injected into the carotid artery of anesthetized rabbits and traced in the brain tissue by means of electron microscopy. Dose-dependent increase in colonic temperature was induced by intravenous injection of used IL-1 in rabbits, while heated IL-1 beta lost the pyrogenicity. Injection of solution of colloidal gold per se did not affect the colonic temperature of afebrile conscious rabbits. However, the IL-1/gold conjugates induced fever; IL-1 beta retained its pyrogenic potency even after labeling with gold. By electron microscopy, the IL-1/gold conjugates were observed on the surface and in the vesicle of endothelial cells of the capillary in the region of the anteroventral third ventricle. This implies that circulating IL-1 acts, as the initial step to induce fever, on the endothelium in that region.

[Effect of propiverine hydrochloride on the function of the bladder in decerebrated dogs]

The effect of propiverine hydrochloride (P-4) on the function of the bladder in decerebrated dogs was compared with that of propantheline, an anticholinergic drug which is used for the treatment of micturitional disorders. P-4 (5 and 10 mg/kg, i.v.) significantly increased maximum vesical volume (Vmax); and at the dose of 10 mg/kg, i.v., it also significantly increased effective vesical volume (EV) when determined by cystometry. However, at the dose level of 2, 5 and 10 mg/kg, i.v., P-4 had no effect on residual volume (RV) after micturition contraction. Propantheline (0.25 and 0.5 mg/kg, i.v.) also significantly increased Vmax, but showed no effect on EV. At doses higher than 0.016 mg/kg, i.v., propantheline significantly increased RV. These findings indicate that P-4 is a useful drug for the treatment of pollakiuria.

[Effects of propiverine hydrochloride (P-4) and its metabolites on urinary bladder function in anesthetized rats]

The effects of P-4 and its active metabolites, 1-methyl-4-piperidyl diphenylpropoxyacetate N-oxide[P-4(N----O)], 1-methyl-4-piperidyl benzilate N-oxide [DPr-P-4 (N----O)] and 1-methyl-4-piperidyl benzilate hydrochloride (DPr-P-4), on urinary bladder function were investigated in urethane anesthetized rats. By cystometrography, P-4 (2, 4 mg/kg, i.v.) and P-4 (N----O) (4 mg/kg, i.v.), which have direct action on smooth muscles, significantly increased the maximum vesical volume. As for rhythmic bladder contractions, P-4 (1,2,4 mg/kg, i.v.) and P-4 (N----O) (2, 4 mg/kg, i.v.) significantly decreased the frequency with a slight decrease in the amplitude. On the other hand, DPr-P-4 (N----O) (0.1, 0.5 mg/kg, i.v.) and DPr-P-4 (0.01, 0.05 mg/kg, i.v.), which have anticholinergic effects, significantly inhibited the maximum vesical pressure on the cystometrograms, and DPr-P-4 (N----O) (0.1, 0.5 mg/kg, i.v.) and DPr-P-4 (0.005, 0.05 mg/kg, i.v.) significantly inhibited the amplitude of the rhythmic bladder contractions. The effects of flavoxate and papaverine were similar to those of P-4 and P-4 (N----O), but the effects of propantheline and atropine were similar to those of DPr-P-4 (N----O) and DPr-P-4 in these two experimental methods. These results suggest that the clinical effects of P-4 are based not only on the actions of P-4 itself but also on those of its active metabolites.

[Effects of propiverine hydrochloride and its metabolites on isolated guinea pig urinary bladder]

The effects of P-4 and its active metabolites in human blood and urine and the effects of 1-methyl-4-piperidyl diphenylpropoxyacetate N-oxide [P-4(N----O)], 1-methyl-4-piperidyl benzilate N-oxide [DPr-P-4(N----O)] and 1-methyl-4-piperidyl benzilate (DPr-P-4) on isolated guinea pig urinary bladder were investigated. At doses of 10(-6) or 10(-5) M, P-4 shifted the dose-response curve for acetylcholine (ACh) to the right, and at a dose of 10(-5) M, it also inhibited the maximum response of ACh. At doses of 10(-5) M or more, P-4(N----O) inhibited the maximum response of ACh. DPr-P-4(N----O) or DPr-P-4 shifted the dose-response curve for ACh to the right at doses of 10(-6)-10(-4) M or at doses of 10(-7)-10(-5) M. P-4 at doses of 10(-6) M or more inhibited the KCl (100 mM)-induced contraction in a dose-dependent manner, and its potency was quite equal to that of terodiline. The inhibitory effect of P-4(N----O), DPr-P-4(N----O) and DPr-P-4 in the KCl (100 mM)-induced contraction were weaker than that of P-4. P-4 and P-4(N----O) had a dose-dependent inhibitory effect on K+-induced 45Ca influx in isolated guinea-pig urinary bladder.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of propiverine hydrochloride on the function of the bladder in dogs]

Propiverine hydrochloride (P-4) is a new derivative of benzilic acid. The effect of P-4 on the function of the bladder in anesthetized dogs was studied in comparison with flavoxate, which is clinically used for the treatment of pollakiuria. P-4 (4 mg/kg, i.v.) caused a significant increase in maximum vesical volume (Vmax), which was estimated by a cystometrogram. A similar effect was also observed following intravenous administration of verapamil (1 mg/kg), while flavoxate (4 mg/kg, i.v.) caused no significant changes in Vmax. P-4 significantly decreased the frequency of rhythmic bladder contractions at doses higher than 1 mg/kg, i.v., whereas flavoxate first revealed a significant decrease at 4 mg/kg, i.v. Thus the inhibitory effect of P-4 on the micturition movements of the bladder is more potent than that of flavoxate. These findings indicate that P-4 is a useful drug for the treatment of pollakiuria.

Effect of indomethacin on febrile response to recombinant human interleukin 1-alpha in rabbits

Effects of indomethacin, a potent inhibitor of prostaglandin (PG) synthesis, on the fever induced by recombinant human interleukin 1-alpha (rhIL 1-alpha) was studied in conscious rabbits. Intracerebroventricularly administered rhIL 1-alpha induced a dose-dependent increase in colonic temperature that was prominently suppressed by pretreatment with indomethacin given either intracerebroventricularly or subcutaneously. On the other hand, fever induced by intravenous administration of rhIL 1-alpha was not completely suppressed by either subcutaneous or intracerebroventricular indomethacin; a small rise in colonic temperature persisted at approximately 45 min after rhIL 1-alpha injection. This rise in colonic temperature was suppressed when indomethacin was given both intracerebroventricularly and subcutaneously. It is suggested that PGs synthesized in the central nervous system contribute to the IL 1 fever and that part of IL 1-alpha given peripherally is also transmitted into the central nervous system to contribute to IL 1 fever.

Antibody to tumor necrosis factor (TNF) reduces endotoxin fever

Antibody to tumor necrosis factor (TNF), injected intravenously, reduced endotoxin fever in the rabbit. The fever-reducing effect was apparent in the latter half of the febrile response.

Regional differentiation of sympathetic nerve activity during fever caused by intracerebroventricular injection of PGE2

In urethane-anesthetized rabbits prostaglandin E2 (PGE2) injected into a lateral cerebral ventricle (icv) produced hyperthermia. During the phase of rising rectal temperature, renal sympathetic activity monitored by multi-unit recording was reduced while the drop of ear skin temperature indicated cutaneous sympathetic activation. These reciprocal changes in activity corresponded to those typical for cold stress as well as for the phase of rising body temperature in fever induced by endotoxic lipopolysaccharides (LPS). However, a slight early stimulation of the heart rate after icv PGE2, contrasted to the initial reductions seen with LPS fever and in the cold. After sino-aortic denervation renal sympathetic inhibition in response to icv PGE2 was reduced but not abolished. After cervical vagotomy the antagonism between cutaneous and visceral sympathetic activity and the increase in heart rate became more prominent. During the phase of subsiding hyperthermia after icv PGE2, renal sympathetic activity returned to its control level, but, unlike LPS fever, did not exceed it. The results of this study indicate that the reciprocal changes in cutaneous and renal sympathetic activity, but not of sympathetic outflow to the heart, are identical during the phase of rising temperature in PGE2 and LPS fever. During the phase of subsiding hyperthermia, renal sympathetic activities change to different extents in PGE2 and LPS fever.

Fever and fever syndrome--current problems

Research into the complex humoral and neurophysiological events of pyrogen-induced fever has proceeded rapidly to establish the thermal and non-thermal components of the fever syndrome. The major breakthroughs derive from the elucidation of the identity of the endogenous pyrogen interleukin 1 with the humoral factors responsible for the acute phase reaction and for the activation of lymphocytic, cellular, and immunological defence as host responses to infections. As a consequence, fever research is no longer concerned primarily with the changes in temperature regulation responsible for the febrile alteration of temperature regulation, but aims at the elucidation of the contributions that are made by both the thermal and non-thermal components of the fever syndrome to the defence of the host against the microbial intruder responsible for this syndrome. In order to account for this development in these introductory remarks to the current issues of fever research, this review has tried to pay particular attention to the following points: 1) The role of humoral factors in the generation of febrile hyperthermia, including endogenous pyrogens as well as mediators acting on the thermoregulatory center. 2) The "fever syndrome" with special consideration of its regulation and of the significance of its components from the viewpoint of fever as a host-defence reaction. 3) The assessment of the role of PG's in the generation of the fever syndrome, both as putative central mediators and as systemically released agents, with special consideration of the inhibitory action of the established antipyretic drugs on PG synthesis.

Threshold dissociation of thermoregulatory effector responses in febrile rabbits

When the core temperature stabilizes at a hyperthermic level after iv injection of lipopolysaccharide (LPS), the threshold core temperature for cutaneous vasoconstriction (Thcv) is significantly increased in hot and neutral environments, while the threshold core temperature for shivering (Thsh) is not significantly altered in hot or cold environments but is significantly reduced at thermoneutrality. This type of dissociated threshold alterations of thermoregulatory effector responses seems to be typical for the febrile response of rabbits to LPS. Because the same threshold dissociation can be demonstrated after icv injection of LPS, the systemic and the central effects of LPS in the generation of fever seem to be mediated by identical mechanisms. Prostaglandins of the E series (PGE), one of the mediators considered as important in fever generation, cause parallel increases in Thcv and Thsh when injected icv. This indicates that the mode of action of PGE on the central targets producing hyperthermia differs from that of the ensemble of mediators involved in the generation of LPS fever in rabbits. In rabbits pretreated with aspirin, the threshold dissociation after iv LPS injection still occurs. This indicates that factors other than PGE play an important role in the generation of the threshold dissociation of thermoregulatory effector responses, which is typical for LPS fever. These data indicate also that the states of activity of the thermoregulatory effectors involved in the febrile responses can be altered individually and that the activities of these effectors during LPS fever are quite different from their activities in the control state.

Hypothermia enhances acetylcholine-induced contraction of isolated rat ileum

The amplitude of acetylcholine (ACh)-induced contraction of isolated rat ileum was enhanced at medium temperatures lower than normal body temperature. Maximum enhancement was achieved between 30 and 25 degrees C. Changes in medium pH and activities of the enteric nervous system due to temperature changes were not essential for this enhancement.

Characteristics of cardiovascular responses of the bullfrog (Rana catesbeiana) to thermal stimulation of the spinal cord

Selective thermal stimulation of the spinal cord caused changes in ventricular pressure (VP) and blood flow of the pulmocutaneous artery (PCBF) in the bullfrog, Rana catesbeiana, anaesthetized with urethane. Warming the spinal cord significantly increased VP from 28.4 +/- 2.5 to 37.2 +/- 3.5 mmHg (n = 8) and PCBF from 24.5 +/- 1.4 to 29.5 +/- 2.0 ml/min (n = 5). Spinal cord cooling significantly decreased VP from 29.3 +/- 2.5 to 24.0 +/- 1.9 mmHg (n = 6) and PCBF from 22.4 +/- 1.4 to 18.5 +/- 1.7 ml/min (n = 5). Although heart rate did not exhibit significant changes during thermal stimulation, changes in cardiac output were achieved by changes in VP, i.e. changes in stroke volume. Changes in VP were antagonized with propranolol, but not influenced by lower sympathectomy which eliminates the catecholamine release for the chromaffin tissue. Atropine significantly increased resting PCBF but failed to antagonize changes in PCBF. This shows that changes in PCBF during spinal cord thermal stimulation are not mediated by an active vasomotor mechanism, but result from changes in cardiac output. The present results show that changes in spinal cord temperature induce inotropic effects on the bullfrog heart through a beta-adrenergic mechanism of sympathetic nervous origin.

Comparison of the action of prostaglandin with endotoxin on thermoregulatory response thresholds

Prostaglandin E2 (PGE2) and lipopolysaccharide (LPS) derived from E. coli were injected into the lateral cerebral ventricle of rabbits at 30 degrees C ambient temperature. The threshold core temperatures for ear cutaneous vasoconstriction (Thv) and shivering (Thsh) were determined by whole-body cooling with an intestinal thermode. Each threshold, as determined at the plateau phase of LPS fever and PGE2 hyperthermia respectively, were compared with the control values before LPS and PGE2 injection. Thsh was not changed by the injection of LPS, while Thv was increased. After PGE2 injection both Thsh and Thv were increased in comparison to their control levels. These changes paralleled the elevation of core temperature. The present study does not exclude prostaglandins as humoral mediators involved in some of the central processes generating fever, but suggest at the same time that there are additional properties of LPS fever for which prostaglandins do not account.

Cardiovascular responses of the bullfrog (Rana catesbeiana) to thermal stimulation of the spinal cord

Selective thermal stimulation of the spinal cord was performed in the bullfrog (Rana catesbeiana). Spinal cord warming caused an increase in systolic pressure of the truncus arteriosus, and cooling caused a decrease. Spinal cord warming caused an increase in systolic and pulse pressures of the conus arteriosus, and cooling caused a decrease. These results showed the temperature perceptibility of the spinal cord and a relationship between spinal cord temperature and autonomic functions in the frog as in other endothermic and ectothermic species.

Inhibitory effect of alpha-alpha-diphenyl-alpha-propoxyacetic acid-L-methyl-4-piperidyl ester hydrochloride on the activity of the rat urinary bladder

alpha-alpha- Diphenyl-alpha- propoxyacetic acid-l-methyl-4-piperidyl ester hydrochloride(propiverine) significantly decreased the volume-pressure ratio of the rat urinary bladder and suppressed efferent nervous activity of the bladder branch of the pelvic nerve during vesical extension.

Increase in oxygen consumption induced by selective spinal cord cooling in the exercising pigeon

Six domestic pigeons with chronically implanted spinal thermodes were exercised on a treadmill at neutral ambient temperature. During the exercise the spinal cord was cooled to 34.7 +/- 0.4 degrees C (mean +/- S.E.M.). Oxygen consumption of the pigeons increased from 28.3 +/- 2.1 to 61.2 +/- 3.7 ml X min-1 X kg-1 due to exercise per se, and superimposed cooling of the spinal cord during exercise induced an additional increase in oxygen consumption to 84.9 +/- 4.5 ml X min-1 X kg-1. The result demonstrates that cooling of the spinal cord elicits shivering in exercising pigeons at thermoneutral conditions.

Renal sympathetic baroreflex during normoxia and during hypoxia in conscious and in anesthetized rabbits

The responses of renal sympathetic nerve activity (RSNA) to changes in mean arterial pressure (MAP) during normoxia and hypoxia was studied in conscious rabbits and during anesthesia with pentobarbitone (PB) by determining the RSNA baroreflex curves. In conscious rabbits, the gain in RSNA response was greater and the range of MAP between minimum and maximum levels of RSNA was narrower than in anesthetized rabbits. The renal sympathetic baroreflex was augmented by hypoxia, indicating a central excitatory interaction between the effects of baro- and chemoreceptor stimulation. However, hypoxia produced no significant change in median blood pressure. During anesthesia with PB, resting MAP was decreased, median blood pressure was lowered, and renal sympathetic baroreflexes were less pronounced. Renal sympathetic baroreflex was augmented by hypoxia, and there was a significant increase in median blood pressure. These results provide direct evidence of an inhibitory effect of PB on the response of RSNA to baro- and chemoreceptor stimulation.

Renal and cutaneous vasomotor and respiratory rate adjustments to peripheral cold and warm stimuli and to bacterial endotoxin in conscious rabbits

In conscious rabbits peripheral cold stimuli decreased respiratory rate and increased cutaneous vasomotor tone while simultaneously renal sympathetic nervous discharge decreased. Peripheral warm stimuli produced the reverse pattern of autonomic effector activity. Injection of a bacterial endotoxin at warm ambient temperature elicited a biphasic fever response. Within the first 60 min cutaneous vasomotor tone increased, simultaneously renal sympathetic activity decreased. Therefore, ear skin vessels dilated and renal sympathetic activity increased by about 100%. Respiratory rate remained depressed during both fever phases. Renal blood flow was investigated in a second series of experiments and showed a negative stimulation but only in the first phase of fever. The results show that renal innervation is involved in the typical thermoregulatory autonomic activity pattern by which temperature homeostasis is preserved. The vasomotor patterns of cold and heat stress developing during fever are compatible with the concept of a changed set-point of the body thermostat. The depressed respiratory rate and the lack of the renal vascular response to the increased nervous activity during the second fever phase and their reversal to normal after acetylsalicylate (ASA) indicate the participation of prostaglandins modifying peripheral and central neurotransmitter mechanisms.

Antagonistic changes of gastric and colonic motility during selective thermal stimulation of thoracic and lumbosacral cords in anesthetized dogs

Changes in gastric and distal colonic motility evoked by thermal stimulation of the thoracic and lumbosacral cords, either individually or simultaneously, were investigated in spinal-intact dogs and in dogs spinalized at the cervical level. Simultaneous cooling of the thoracic and lumbosacral cords increased both gastric and colonic motility before and after spinalization. The direction of the responses evoked by simultaneous heating was the opposite, but only the decrease in gastric activity in the spinal-intact dog was significant. Selective cooling of the thoracic cord increased gastric motility, but decreased colonic motility before and after spinalization. Selective heating decreased gastric motility before and after spinalization, and increased colonic motility before spinalization. Selective cooling of the lumbosacral cord decreased gastric motility and increased colonic motility in spinal-intact dogs. No significant responses could be observed during selective heating in spinal-intact dogs. However, in spinalized dogs, the selective cooling and heating increased and decreased colonic motility respectively, while no significant change was observed in gastric motility during the cooling and the heating. It is concluded from the results that thermal stimulation of the spinal cord directly affects spinal functions which control gastrointestinal motility, and that there exists a mutual inhibitory interaction between the thoracic and lumbosacral innervation of the gastrointestinal tract.