Depletion of cardiac vagal motoneurons in the diabetic rat: a wheat germ agglutinin-horseradish peroxidase neurohistomchemical study

The projections of vagal neurons to the heart were studied in streptozotocin-induced diabetic Sprague-Dawley rats using the Wheat germ Agglutinin-Horseradish peroxidase (WGA-HRP) neural tracing technique. Experimental rats were rendered diabetic by intraperitoneal injection of streptozotocin (STZ) in 0.5 M citrate buffer at pH 4.5 in a dosage of 60mg/kg body weight. The rats became diabetic within 24 hours of treatment with streptozotocin. The diabetic rats were maintained in a stable diabetic state by daily injections of insulin for 16 weeks. Age-matched control rats were injected intraperitoneally with the same volume of citrate buffer not containing STZ. The blood glucose level of control rats was confirmed to be within normal range prior to and 24 hours after injection. with citrate buffer. Control rats were also kept alive for 24 hours after citrate buffer injection. At the end of 24 hours the treated and control groups were injected with WGA-HRP, and sacrificed 48-72 hours after tracer injection. Transverse serial sections of frozen brainstem were prepared, processed for WGA-HRP neurohistochemistry, and examined under light and dark field microscopy. The analyses of the sections taken from the chronic diabetic rats revealed further WGA-HRP neurons in the nucleus ambiguous (nA) than sections taken from the control normoglycaemic rats. There was also sporadic labelling of the dorsal motor nucleus of the vagus nerve (DMNV) in the control rat but none at all in the diabetic rats. The depletion of labelled neurons in the diabetic rats compared with the normoglycaemic rats is indicative of impairment of retrograde neuronal transport of WGA-HRP in chronic diabetic state.

The localization of cardiac vagal motoneurons in the medula of the ferret (Mustela Putorius Furo)

Using the Horseradish peroxidase (HRP) retrograde axonal transport labelling technique, the central origins of cardiac vagal preganglionic neurons were investigated in the ferret. The atrial and ventricular walls of the heart were injected with HRP following exposure of the heart through a left thoracotomy. A set of control ferrets was injected in the same manner as the experimental rat with normal saline, while another set was injected with HRP after bilateral cervical vagotomy. The last set of control ferrets received HRP injections into the lest ventricular cavity. After 48-72 hours of survival period, serial transverse frozen sections of the brainstem and upper spinal cord were taken and processed for HRP neurohistochemistry using the tetramethylbenzidine method as earlier described by Mesulam (1,2.). Examinations of the sections under bright and dark-field illumination revealed the presence of HRP labeled neurons bilaterally in the nucleus ambiguus (nA). Few labeled neurons were also seen in the dorsal motor nucleus of the vagus nerve (DMX). HRP labeled neurons were not seen in any of the control sets. It is concluded that the heart in the ferret receives its' vagal preganglionic innervation principally from the nA and partly from the DMX (AU)

The Jamaican body's role in emotional experience and sense perception: feelings, heart, minds and nerves

When Jamaican speak of feelings, they literally mean feelings: physical sensations. Emotions, which emerge through social interaction, comprise an unmarked subset of feelings. They can affect the mind in ways that are actualized in behavior. Emotions affect other parts of the body as well, in ways that follow from an equilibrium model of health. Non-emotional feelings index bodily disequilibrium rather than causing it. An example of such is seen in nerves: a chronic feeling-complaint that comes about when the nerves, associated with perception and sensation, are weakened, and which entails visual dimness, jumpiness, and joint trouble. Although exacerbated by certain social situations and often used in social commentary and manipulations, nerves is experienced and treated as a physical rather than a socially-based disorder. By studying the bodily dimension of nerves and other feelings we may gain insight into the ways in which the body serves as a source of culture (e.g., nerves culture) as well as into how culture influences bodily experience. We may broaden our understanding of the complex interplay between the bodily and mental dimensions of people's lives.(AU)

Myocardial perfusion scintigraphy using Tc99m labelled compounds: correlation with coronary angiography

The increasing incidence of ischaemic heart disease with high mortality rate and the recent introduction of Tc99m labelled myocardial perfusion imaging agents, along with the advent of a coronary angiography programme in Trinidad and Tobago, prompted the comparison of the sensitivity and specificity of myocardial perfusion scintigraphy (MPS) with coronary angiography (CA). Using a standard one-day code-differential imaging protocol single photon emission computed tomography (SPECT), images of the left ventricular myocardium of 30 patients were obtained at rest and following exercise: These images were analyzed for perfusion defects to assess each of the three main coronary arteries; the left anterior descenting artery (LAD), the right coronary artery (RCA) and the left circumflex artery (LCx). The data were then correlated with the angiographic findings. MPS yielded an overall sensitivity of 97.5 percent and a specificity of 83.6 percent when compared to CA. Discordant data were obtained in the analysis of nine vascular territories with scintigraphy producing eight false positive and one false negative. The false positive cases were seen in two males and four females. Of the males, one was discovered to have intramyocardial tunnelling of the LAD artery and the other demonstrated differential perfusion between the LAD and LCx arteries. Of the females, one was classified as having Syndrome X and another demonstrated differential perfusion between the LAD and LCx arteries; the other two cases were attributed to breast attenuation. The one false negative was obtained in a patient who demonstrated good collateral circulation on angiography. MPS thus compares very well with CA in assessing the three main myocardial vascular territories (AU)

Blood pressure levels and cardiothoracic ratios of a mixed African West Indian community

In Plymouth-Bethesda, Tobago, blood pressures and cardiothoracic (CT) ratios in a censused total adult population. Blood pressure levels rose across the age groups in both sexes and were similar to those of other West Indian communities and of most African studies. Most of the hypertensives were not on treatment at the time of interview. Mean CT ratios are similar to those of Jamaican and Guyanese mixed Africans and appear not to be associated with the high prevalence of ECG criteria for left ventricular hypertrophy. The latter was predominant in men and the high CT ratios in women. CT ratios increased with hypertension. For men, highest correlation for systolic and diastolic blood pressures was with Quetelet's Index. For women, highest correlations were repectively with post-load blood sugar levels and Quetelet's Index. (AU)

Heart size and chest shape in homozygous sickle cell disease

The hoop-shaped chest is a well-recognised but unexplained feature of the abnormal anthropometry of SS disease, developing in children by the age of 4-6 years. The hypothesis that cardiomegaly may influence abnormal chest growth has been tested by examining the relationship between cardiac volume and the antero-posterior/lateral chest diameter ratio in children aged 6-8 years. The finding of a significant positive correlation supports this hypothesis (AU)

Radiological evaluation of the cardiac apex in Jamaican children

The position of the clinical apex beat projected on chest radiographs was compared to different points on the cardiac outline which have been regarded as the radiological apex. Good correlation was found between the clinical apex and the most lateral point of the left cardiac border, but not with the cardiophrenic angle of the lower end of the long diameter of the heart. The mid-clavicular line cannot be used to define the upper limit of the normal sized heart on radiographs as in clinical practice, because in many of the subjects the heart extended outside the mid-clavicular line (AU)

The prediction of postoperative potassium excretion after cardiopulmonary bypass

Potassium excretion following cardiopulmonary bypass has been studied in 11 patients. After an initial period of 4 to 5 hours, potassium excretion was found to be directly related to urine flow provided diuretics had not been administered. Triamterene altered the slope of the regression line so that, for any given urine flow rate, less potassium was excreted. A simple program for postoperative potassium therapy is described (AU)

The possible relationship between cardiac glycogen levels, ouabain toxicity and the anti-arrhythmic effect of anacardium occidentale

Using the open chest dog with the heart in situ, the influences upon the cardiac glycogen by fasting, anacardium occidentale, and ouabain were studied. Fasting elevated the cardiac glycogen while intravenous infusion of glucose did not increase the cardiac glycogen. Anacardium occidentale elevated the cardiac glycogen after a slow intravenous infusion. The depletion of cardiac glycogen occurred concurrently with the onset of ectopic beats due to ouabain toxicity, and the toxic dose of ouabain was significantly increased in relation to the high cardiac glycogen. The stress of cardiac surgery significantly depleted the glycogen content of the human heart, and this depletion was not related to trauma or the time the patient was on cardio-pulmonary by-pass. It is concluded that: (a) anacardium occidentale protects against ouabain arrhythmias by elevating the cardiac glycogen, (b) there is a critical cardiac glycogen level below which ouabain readily becomes toxic, and (c) surgery on the heart in the human depletes its glycogen stores (AU)

American trypanosomiasis in British Honduras: VIII. The morphogenesis of Trypanosoma (Schizotrypanum) cruzi in the tissues of animals experimentally infected with British Honduras strains of the parasite

The cycle is described of the intracellular development of British Honduras strains of Trypanosoma (Schizotrypanum) cruzi in the tissues of experimentally infected animals. From studies and observations on a considerable amount of material it is concluded that the morphogenesis of T. cruzi in tissues includes the amastigote, sphaeromastigote, epimastigote and transitional trypomastigote forms, leading to the formation of the bloodtype trypnosome. It is suggested that, in order to clarify the long-standing controversy on the morphogenesis of the parasite, more detailed studies are required on the characteristics and variations of T. cruzi strains from other geographical localities where Chagas' disease is epidemic.(Summary)

Two unusual cases of mural endocarditis, with a review of the literature

Two unusual cases of mural endocarditis are described. The first was that of a 13-year-old boy with infected burns of the legs. Autopsy revealed mural vegetations in both ventricles and cytomegalic viral inclusions were demonstrated in the vegetations, heart muscle, and endothelial cells of various organs. This appears to be the first reported case of cytomegalic inclusion viral endocarditis. A review of the literature revealed only six previous reports of cytomegalic viral myocarditis, which was also present in this case. The second case was that of a 4-year-old girl with bronchiectasis. Autopsy revealed mural vegetations in the right ventricle. Group C beta-hemolytic steptococcus was isolated from th mural vegetations, as well as from the diseased lungs. Only two previous reports of endocarditis caused by this organism are found in the literature (AU)

American trypanosomiasis in British Honduras. V. Development of Trypanosoma (Schizotrypanum) cruzi in animals infected with strains isolated in the El Cayo District, and the occurrence of crithidia forms in the tissues

The morphology is described of the tissue stages of Trypanosoma cruzi observed in strains isolated in British Honduras. The persistent presence of crithidia forms of the parasite in infected vertebrate tissues suggests that T. cruzi strains found in British Honduras differ from strains described from other geographical areas. It is suggested that such strains may be suitable for studies on trypanocidal drugs in vivo and for comparative studies on the morphology of reproduction in tissues. (AU)

American trypanosomiasis in British Honduras. VI. A natural infection with Trypanosoma (Schizotrypanum) cruzi in the opossum Didelphis marsupialis (Marsupialia, Didelphoidea), and experimental investigations of different wild-animal species as possible reservoirs for the parasite

The occurrence is described of a natural infection with Trypanosoma (Schizotrypanum) cruzi in the common opossum, Didelphis marsupialis, captured in El Cayo District, British Honduras. The identity of the parasite was established from histological sections if the heart muscle, which showed pseudocysts filled with leishmania forms. Seven species of wild animal were experimentally infected with T. cruzi. Rats of the species Heteromys desmarestianus, Ototylomys philotis, Tylomys nudicaudus and Oryzomys sp. were all highly susceptible to the parasite and developed a fatal illness. It ie concluded that these species are unlikely to act as natural reservoirs for T. cruzi, but that they may prove useful in further experimental studies on the parasite and for the passage of strains. A rat of the species Nyctomys sumichrasti showed a high resistance to the infection; only scanty intracellular forms of T. cruzi were found in heart-muscle smears, and chagastic pseudocysts were present in small numbers in histological sections of the heart muscle. Results similar to those obtained with the Nyctomys rat were observed in a coati (Nasua narica), which also showed a high resistance to the challenge . No intracellular forms of T. cruzi were found in the heart muscle, but they were present in small numbers in the liver and spleen; they were morphologically identical to those seen in the heart muscle smears from the Nyctomys rat. No infection developed in two young grey foxes (Urocyon cinereo-argenteus) when challenged with a highly virulent strain of T. cruzi. It is concluded that these animals are unlikely to act as natural reservoirs for the parasite in British Honduras. It is believed that, although experimental inoculation of wild animals with T. cruzi may be prejudiced by their possible previous contact with the parasite, the results may give some indication of the nature of possible reservoir-hosts. (AU)

A comparitive study of virulences, plaque morphologies and antigenic characteristics of Venezuelan encephalitis virus strains

Virulences of VE virus strains from tropical regions of the North and South American continents were studied in adult Syrian hamsters, Swiss albino mice and cotton rats. Virulence profiles were based on frequency and time of illness and death following subcutaneous inoculation of small doses of virus as collected in nature or after only a few passages in laboratory hosts. Forty-one strains from Mexico, USA-Florida, Panama, Colombia, and Venezuela uniformity killed hamsters inoculated s.c. with 4-1000 PFU; incubation periods were usually 3-6 days, but some Panamanian and USA-Florida strains had incubation periods 1-2 days longer than strains from other countries. All of 37 strains from these countries regularly produced illness in adult mice, but killed only 71-82 percent; in adult cotton rats, signs of illness were not recognized, but death occurred in 18-30 percent. Variations in virulence profiles for mice and cotton rats among 28 Mexican strains were ogten as great as those seen among 9 strains from USA-Florida, Panama, Colombia and Venezuela. Virus strains from the Bush Bush areas of Trinidad, however, had distinctive virulence profiles. All 5 of these strains killed hamsters only after prolonged incubation periods of more than 5 days, and killed only 1 of 25 mice; neither of two strains killed cotton rats. Young and Johnson reported (Amer. J. Epid., 1969, 89 286-307) that these Trinidad strains should antigenically be classified as Mucambo rather than VE virus. The TC 83 attenuated strain of VE virus in a dose of 500 PFU given s.c. killed no hamsters, mice or cotton rats, but in some experiments employing larger doses, up to 20 percent hamsters became ill and 5-10 percent died without apparent relationship to dose. Plaque sizes and morophologies of 19 VE and 5 Trinidad Mucambo virus strains in primary chicken embryonic cell cultures did not correlate with virulence for hamsters, mice, cotton rats or man, nor with geographic, host or tissue source or year of collection. In sera of cotton rats and mice 3-4 weeks after s.c. inoculation, titers of VE virus HI antibody measured with hemagglutinin from a Mexican virus strain were similar for strains from Mexico, Colombia and Venezuela. However they were lower with USA-Florida and TC 83 virus strains and with Trinidad Mucambo virus strains, suggesting that these viruses differ antigenically from Mexican, Colombian and Venezuelan strains. Nevertheless the attenuated TC 83 vaccine virus protected adult mice against s.c. challenge by 28 Mexican and 8 other VE virus strains from USA-Florida, Panama, Colombia and Venezuela, suggesting that immunologically distinct types of VE virus based on cross-protection do not exist in these countries. (AU)

Cardiothoracic ratios in two Jamaican communities

Ashcroft, M. T. and W. E. Maill (Med. Research Council's Epidemological Research Unit, Univ. of the West Indies, Kingston 7, Jamaica). Cardiothoracic ratios in two Jamaican communities. Amer. J. Epid., 1969, 89: 161-167.-Cardiothoracic ratios were estimated from 929 full-sized chest radiographs of representative samples of men and women of predominantly African origin aged 35-64 years living in rural and suburban communities in Jamaica. CTRs were greater in women than in men and increased with age; they were orrelated with weight and with blood pressure levels. Mean CTRs were substantially greater in Jamaica than in a comparable sample of white persons living in Wales. These differences could not be explained by the prevalence of cardiovascular disorders including hypertension or by differences in weight or physical activity. An ethnic difference, possibly in the position of the heart within the chest or in the size of the thoracic diameter, is suggested. The greater CTR of the Negro should be taken into account when assessing heart size from chest films. (AU)