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Biomedical subjects

J Townsend

Publications and source records attributed to J Townsend.

At least 127 records · Page 7Linked to original sources
PubMed1985

Prevention of defective axonal transport in streptozocin-diabetic rats by treatment with "Statil" (ICI 128436), an aldose reductase inhibitor.

This investigation examined the effect of treatment of streptozocin-diabetic rats with the aldose reductase inhibitor "Statil" (25 mg/kg/day p.o.) on axonal transport in cholinergic neurons of the sciatic and vagal nerves and on nerve polyol and sugar levels. Three weeks of experimental diabetes caused deficits in the accumulation of choline acetyltransferase activity proximal to 24-h constrictions in the left sciatic and vagus nerves. These deficits did not develop in age-matched, similarly diabetic rats that were treated with the aldose reductase inhibitor. The inhibitor prevented completely the build-up of sorbitol and markedly reduced the build-up of fructose in the sciatic nerves of the treated diabetic rats. The inhibitor also prevented the depletion of myo-inositol that was seen in the untreated diabetic animals. It is suggested that these findings indicate a possible approach to the elucidation of the pathogenesis of cardiac vagal dysfunction in diabetes mellitus.

Animals↗
PubMed1985

[Synopsis of the Seminar on Breast Feeding Promotion in Central America, Panama and the Dominican Republic. Isla Contadora, Panama, 1983].

The most recent and reliable information on the status of breast-feeding in Central América, Panama and the Dominican Republic indicates that during the last decades, in all of these countries there has been a decrease in the prevalence and duration of breast-feeding. In some of them, this situation would seem to be reverting. Considering the importance that breast-feeding has on children's health and nutrition, the Institute of Nutrition of Central America and Panama (INCAP), organized a Regional Seminar on the Promotion of Breast-feeding, which was held in Contadora Island, Panama, in April, 1983. Based on the discussions of the working groups, sectoral and integrated recommendations were formulated for the purpose of promoting breast-feeding. This document contains specific recommendations for each of the sectors represented in the Seminar.

Breast Feeding↗
PubMed1985

[Breast feeding practice and activities for its promotion in Central America, Panamá and Dominican Republic].

This paper summarizes the data presented by the representatives of Central America, Panama and the Dominican Republic at the II Regional Seminar on the Promotion of Breast-Feeding, held in Isla Contadora, Panama, April 25-29, 1983. The representatives of Costa Rica, Honduras and Panama provided up-to-date, representative data in regard to the breast-feeding practice. The average weaning age in the urban and rural areas of Costa Rica is 6 and 4 months, respectively. In Honduras and Panama, 43 and 17% of the infants from urban areas, and 21 and 37% of the babies from rural areas, respectively, were weaned before they reached four months of age. The need for availability of permanent systems to collect information on the breast-feeding practice in the different countries is pointed out. With regard to promotion actions, the absence of a national policy in favor of breast-feeding is evident. Moreover, in the national education systems, little importance is given to the subject. On the other hand, the advances achieved by some hospitals in favoring breast-feeding are mentioned. These include rooming in, the feeding of colostrum to newborns, and the establishment of human milk banks to feed premature babies whose mothers are unable to breast-feed them. Another acknowledged fact is that in the rural areas the agricultural home educators do not reinforce the breast-feeding practice. Also, there is a lack of information on the fulfillment of laws instituted for the protection of pregnant and lactating mothers, as far as pre and postnatal rest is concerned.

Breast Feeding↗
PubMed1982

An ultrastructural study of the interaction in vitro between Trypanosoma theileri and bovine leucocytes.

Bovine neutrophils, eosinophils and macrophages obtained from the mammary gland were cytotoxic to Trypanosoma theileri epimastigotes in vitro in the presence of specific antibody. A detailed ultrastructural study revealed that all types of effector cell phagocytosed T. theileri despite the relatively large size of this parasite (10-130 microns). Phagocytosis proceeded in the classical manner by envelopment of the trypanosome by long pseudopodia. With eosinophils and macrophages structural damage of the parasite was only observed following ingestion. There was evidence of inter-granule fusion in eosinophils prior to the discharge of granule contents into the parasitophorous vacuole; following degradation of the parasite in eosinophils some phagolysosomes opened to the exterior and released what appeared to be trypanosome debris. While eosinophils required less than 30 min to initiate serious damage to the parasite, macrophages required in excess of 2 h to produce similar damage. Conversely, neutrophils caused severe damage within 5 min. An important feature of neutrophil-mediated cytotoxicity was the extensive structural damage to the parasite that was observed before closure of the phagosome. Initially this damage was observed at the end of the trypanosome that was in contact with the neutrophil. This finding suggests that neutrophil-mediated killing of T. theileri is a combination of both extracellular and intracellular mechanisms.

Animals↗
PubMed1982

Importance of competitive binding in the detection of antigen specific bovine isotypes and subisotypes by the micro ELISA.

An enzyme-linked immunosorbent assay was developed to detect and quantify the specific bovine immunoglobulin class response to Trypanosoma theileri, Dictyocaulus viviparus and infectious bovine rhinotracheitis virus. Comparative measurement of the specific immunoglobulin classes in whole serum was achieved using monospecific rabbit antibovine IgG1, IgG2 and IgM, followed by a goat anti-rabbit Ig-enzyme conjugate (antiglobulin ELISA). The results obtained in the antiglobulin ELISA compared favourably with the standard (or indirect) ELISA using the purified immunoglobulins. Competitive inhibition between specific immunoglobulins of different isotypes and subisotypes was the major disadvantage of the antiglobulin ELISA. This latter assay failed to detect specific IgG2 against T theileri antigen in both calf and adult whole serum. The inability to detect the specific IgG2 was a result of competitive inhibition by specific IgG1. However, competitive inhibition between specific immunoglobulins was not observed in either of the other test systems using D viviparus and infectious bovine rhinotracheitis virus antigens.

Animals↗
PubMed1982

Trypanosoma theileri: antibody-dependent killing by purified populations of bovine leucocytes.

Bovine leucocytes were assayed for their cytotoxic activity against Trypanosoma theileri, a large haemoflagellate parasite of cattle. Cytotoxicity was assessed by 3H-uridine release from pre-labelled parasites and also by light microscopy. Cytotoxicity proved to be totally dependent upon the presence of specific antibody. Serum and the immunoglobulin fraction of colostrum from normal adult cattle and serum from normal colostrum fed calves mediated cytotoxicity; serum from SPF colostrum deprived calves possessed no cytotoxic activity. Neutrophils, eosinophils, monocytes and macrophages obtained from both the peripheral blood and mammary gland of heifers were cytotoxic to T. theileri epimastigotes. Lymphocytes failed to mediate cytotoxicity either in the presence or absence of specific antibody. Despite the large size of this trypanosome all effector cells phagocytosed T. theileri. Phagocytosis by macrophages and eosinophils preceded specific isotope release, however neutrophils mediated 50% specific isotope release during the phagocytic period, suggesting extracellular cell-mediated lysis.

Animals↗
PubMed1980

Tumoral calcinosis: evidence for concurrent defects in renal tubular phosphorus transport and in 1 alpha,25-dihydroxycholecalciferol synthesis.

A 50-year-old Latin American man with tumoral calcinosis presented with hyperphosphatemia (6.62 +/- 1.04 SD mg/dl), elevated renal threshold phosphorus concentration (TmP) (7.3 mg/GFR), and 1,25-dihydroxyvitamin D [1,25-(OH)2D] (69 pg/ml) hypercalciuria (239 mg/day), and a high fractional intestinal calcium (Ca) absorption (0.74). Sodium cellulose phosphate therapy (20 g/day) lowered urinary Ca, and partially reduced serum phosphorus (P) and TmP to 5.91 +/- 0.63 mg/dl and 6.2 mg/GFR, respectively. Serum 1,25-(OH)2D remained elevated at 58-64 pg/ml. Amphojel therapy (4 oz/day) decreased urinary P to 23 +/- 21 mg/day and lowered serum P to 5.75 +/- 0.36 mg/dl (P < 0.05). TmP increased to a value of 8.0 mg/GFR while serum 1,25-(OH)2D continued to remain elevated at 53 pg/ml. This case illustrates the probable operation of dual abnormalities in tumoral calcinosis represented by augmented renal conservation of P and an elevation in the circulating concentration of 1,25-(OH)2D.

Calcinosis↗
PubMed1980

Chronic reversible cerebral ischemia: evaluation of a new baboon model.

The authors describe their experience with a baboon model of reversible cerebral ischemia. Middle cerebral artery occlusion was achieved by external compression with an implantable, inflatable balloon cuff in awake, unanesthetized baboons. Selective cerebral angiography confirmed consistent, reliable occlusion. Computed tomography demonstrated early density changes after ischemia, which were reversible with reperfusion. Neurological evaluation demonstrated a "recruitment response" of increasingly persistent deficit with repeated occlusion. Permanent deficits were noted after extensive angiography during periods of occlusion. This was accompanied by the dropout of small vessels in the middle cerebral artery distribution. The results of pathological examinations were consistent with the clinical examinations. No gross or microscopic changes were noted after repeated occlusions that caused deficits like those of transient ischemic attacks. Consistent infarctions were noted in animals with permanent deficits after permanent occlusion or after repeated occlusion and extensive angiography.

Animals↗
PubMed1979

Upward transtentorial herniation: seven cases and a literature review.

Seven cases of upward transtentorial herniation occurred. In each patient, coma with reactive, miotic pupils, asymmetrical or absent caloric responses, and decerebrate posture indicated brain-stem compression. In this setting, the development of unequal, then midposition, fixed pupils signaled midbrain failure from upward herniation. Vertebral angiography showed upward displacement of the superior cerebellar arteries. Results of autopsy confirmed the existence of grooving of the vermis by the tentorial margins and, in one case, of anterior displacement and distortion of the midbrain. In five of 45 reported cases of upward herniation, the conditions were diagnosed antemortem. Instances of cerebellar hematoma and tumor predominated. In at least seven patients, performance of ventriculography may have precipitated herniation. Clinical details were provided in only nine patients and did not separate upward herniation from brain-stem compression. Cerebellar ischemic infarct found in one of our patients is a rarely reported cause of upward herniation.

Adult↗
PubMed1978

Effects of magnesium oxide on the crystallization of calcium salts in urine in patients with recurrent nephrolithiasis.

The effect of oral administration of magnesium oxide on the crystallization in urine of calcium oxalate and brushite was determined in 4 cases of recurrent calcium nephrolithiasis. Each patient was evaluated while on a constant metabolic diet before, during and after therapy with magnesium (1,000 mg. magnesium as magnesium oxide per day). During magnesium therapy urinary hydrogen ion concentration increased by approximately 0.5 unit in all 4 patients and urinary calcium increased about 50 mg. per day in 2. Urinary oxalate decreased significantly in 1 patient and urinary phosphorus was reduced in 2. The urinary activity product ratio of brushite (state of saturation) increased, owing largely to the rise in urinary hydrogen ion concentration but that of calcium oxalate was not changed significantly by magnesium treatment. Although urinary magnesium increased significantly there was no significant change in the urinary formation product ratio (limit of metastability) or the rate of crystal growth of brushite or calcium oxalate. Thus, no beneficial effect of magnesium therapy could be demonstrated in this short-term study.

Administration, Oral↗
PubMed1978

Acetylcholinesterase levels in nasal turbinate congestion.

In a previous communication, one of the authors discussed prolonged congestion of the turbinates following nasal surgery. The clinical factors responsible were allergy or the traumatic effects of nasal packing on the turbinates. A study of turbinate function was done to find the factor responsible for this congestion. Biopsies of an inferior turbinate were obtained preoperatively and two weeks after surgery. The specimens were examined for the level of acetylcholinesterase by histochemical assay and were also studied by examining sections histologically. In the majority of cases, the level of acetylcholinesterase fell with the appearance of congestion and rose when the turbinates returned to normal. These results suggest a connection between turbinate congestion and levels of tissue acetylcholinesterase in the presence of inflammation or allergy.

Acetylcholinesterase↗
PubMed1978

An exaggerated augmentation of renal calcium excretion after oral glucose ingestion in patients with renal hypercalciuria.

The calciuric response to an oral glucose load (100 g) was determined in 16 patients with calcium oxalate urolithiasis (seven with renal hypercalciuria and nine with absorptive hypercalciuria) and seven normal subjects. The rates of renal calcium excretion increased significantly after glucose ingestion in all three groups. The calciuric response in patients with absorptive hypercalciuria and intestinal hyperabsorption of calcium was indistinguishable from that of normal subjects. However, the calcium excretions were significantly higher during 1 hr preceding and 3 hr after glucose ingestion in patients with renal hypercalciuria (with presumed "renal leak" of calcium) than in normal subjects. The increment in the calcium excretion rate was also higher in patients with renal hyperacalciuria, particularly during the 2nd hour of glucose ingestion. The results provide a further support for the concept of different etiologies of renal and absorptive hypercalciurias.

Adult↗