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Biomedical subjects

R Carter

Publications and source records attributed to R Carter.

At least 343 records · Page 19Linked to original sources
PubMed1980

Acute gastric volvulus. A study of 25 cases.

Twenty-five patients with acute gastric volvulus were studied. The two types, organoaxial and mesenteroaxial, are compared with respect to clinical characteristics, diagnosis, pathogenesis and treatment. An understanding of the varied features, including both thoracic and abdominal manifestations, is essential to early recognition and prompt treatment. In addition to Borchardt's triad, this study suggests three important features: (1) minimal abdominal findings when the stomach is in the thorax; (2) a gas-filled viscus in the lower chest or upper abdomen shown by chest radiography (Figure 8), and (3) obstruction at the site of volvulus shown by emergency upper gastrointestinal series. The high incidence of strangulation (28 percent) in this series attests to the urgency of this condition and is a compelling reason for the elective repair of paraesophageal hiatal hernias whenever possible.

Abdomen, Acute↗
PubMed1980

Anti-gamete monoclonal antibodies synergistically block transmission of malaria by preventing fertilization in the mosquito.

Experiments from our laboratory previously demonstrated that infected chickens immunized with gametes of the avian malaria parasite Plasmodium gallinaceum were no longer infectious to the mosquito vector Aedes aegypti and that this transmission-blocking immunity was mediated by antibody. To identify those antigens that are the targets of transmission-blocking immunity, hybrid mouse cell lines secreting monospecific antibodies to surface antigens on male and female gametes of P. gallinaceum have been produced. We describe two such anti-gamete antibodies, 10G3 and 11C7, which act synergistically both to agglutinate male gametes in vitro and to suppress infectivity of parasitized blood fed to mosquitoes. In the presence of a mixture of these antibodies, the male gametes became agglutinated during gametogenesis and failed to detach from the residual body of the gametocyte. In the presence of either antibody alone, the male gametes readily detached during gametogenesis. Neither antibody alone mediated more than a slight reduction in infectivity of gametocytes to mosquitoes. Although both 10G3 and 11C7 recognize surface antigens on both male and female gametes, agglutination and prevention of detachment of the male gametes from the residual body appears to be the primary mechanism by which the mixture of these antibodies prevents fertilization.

Agglutination↗
PubMed1979

Improved glucose control in maturity-onset diabetes treated with high-carbohydrate-modified fat diet.

Fourteen patients with established maturity-onset diabetes were treated as outpatients with a high-carbohydrate-(about 60% of total daily energy requirements)-modified fat diet (ratio of polyunsaturated fatty acids to other fatty acids greater than or equal to 1:1) for six weeks. Commercially available and acceptable cereal foods and tuberous vegetables high in both digestible and non-digestible carbohydrates were used. Simple sugars were restricted. Compared with their usual, low-carbohydrate diabetic diet this diet resulted in a fall in basal plasma glucose concentration (average of values measured at 0300, 0500, and 0700), mean preprandial plasma glucose concentration (average of values measured at 0800, 1230, and 1730), and percentage of glycosylated haemoglobin. Modifying dietary fat also decreased the fasting plasma cholesterol concentration. The findings suggest that it is no longer justifiable to prescribe a low-carbohydrate diet for maturity-onset diabetes.

Blood Glucose↗
PubMed1979

Gamete vaccines and transmission-blocking immunity in malaria.

We have recently proposed an approach to malaria control based on immunization of the host against extracellular malarial gametes, the stage in the mosquito guts, in order to block transmission by the mosquito vector. Our studies with avian and primate models have demonstrated that immunization of the host with extracellular gametes totally suppresses infectivity to the mosquito of a subsequent blood meal. Gametocytes within the erythrocytes are unaffected by the immunity, since resuspending the gametocytes in serum from normal nonimmune animals restores their infectivity to mosquitos. Immunity is mediated by antibodies that are ingested with the blood meal. These antibodies interact with extracellular gametes and prevent fertilization (the fusion of male and female gametes). Thus the infection in the mosquito is blocked, and in this way transmission is interrupted.

Animals↗
PubMed1979

Evidence for environmental modulation of gametocytogenesis in Plasmodium falciparum in continuous culture.

With the introduction of continuous culture of Plasmodium falciparum it has become possible to study the factors involved in gametocyte production in vitro and thus eliminate the uncontrollable in vivo variables of the host. The authors have developed a method for measuring quantitatively the rate of production of gametocytes at any time in such cultures. The method is based on an estimation of the percentage of ring forms that develop into stage II gametocytes.Using this approach, it was found that dilution of cultures with fresh red blood cells so as to lower the parasitaemia led to rapid fall in the rate of conversion to gametocytes. The conversion rates subsequently rose again to levels typically in the order of 10% after several days of growth in the new culture. In the parental cultures from which the dilutions were made, conversion rates remained high at all times. This pattern was consistently observed in three different isolates of P. falciparum from Africa and the results indicate that the reduction of parasitaemia by addition of fresh cells was responsible for reducing production of gametocytes and that conditions associated with a period of growth in culture induced renewed gametocytogenesis. The authors conclude, therefore, that environmental conditions directly modulate the rate of gametocyte production by P. falciparum in culture.After 1(1/2) years in culture, parasites have retained their ability to produce gametocytes and the gametocytes to undergo exflagellation.

Animals↗
PubMed1979

Separation of protoporphyrins and related compounds by reversed-phase liquid chromatography.

We describe the separation of protoporphyrin and related porphyrins by reversed-phase "high-performance" liquid chromatography, with fluorometric detection. We used the method to demonstrate that acid hydrolysis of the dimethyl ester of protoporphyrin IX is complete in 2 to 3 h and is followed by the acid-catalyzed conversion of protoporphyrin IX to a chemical species that chromatographic evidence indicates to be hematoporphyrin IX. In addition, the method was used to evaluate the purity of a commercial preparation of protoporphyrin IX and was also demonstrated to have the sensitivity and specificity needed for measuring the protoporphyrin IX content of whole-blood.

Chromatography, High Pressure Liquid↗
PubMed1978

Treatment of cervical intraepithelial neoplasia with the carbon dioxide laser beam. A preliminary report.

Forty-five patients with histologically proved cervical dysplasia or carcinoma in situ were treated by the carbon dioxide-laser method. The carbon dioxide laser induces cell vaporization by causing intracellular steam combustion stimulated by the emission of a mixture of carbon dioxide, nitrogen, and helium. This method of treatment is easily performed in the outpatient clinic without anesthesia, is inexpensive, and is effective in the treatment of cervical intraepithelial neoplasia. The treatment allows preservation of the transformation zone, thus permitting future colposcopic visualization.

Adult↗
PubMed1978

Aortoesophageal fistula.

With the advent of cardiovascular and bypass procedures, aortoesophageal fistula has progressed from the stage of a pathologic curiosity to a treatable lesion. Although the causes of aortoesophageal fistula are varied, a remarkably consistent clinical picture emerges from study of this condition. Chiari's triad of midthoracic pain, sentinel hemorrhage, and a symptom-free interval followed by fatal exsanguination remains the most important clinical finding today. Although contrast esophagography, esophagoscopy, and aortography are important diagnositc aids, immediate left thoracotomy may be the only means of making the diagnosis and saving the patient when hemorrhage is profuse. In most cases (80 per cent of the present series) there is a symptom-free period varying from hours to days from the original sentinel hemorrhage to the final exsanguination. This permits the informed surgeon trained in cardiovascular technics an opportunity to salvage some of these patients. The various methods of aortic and esophageal repair are discussed.

Aorta↗
PubMed1978

Gamete development in malaria parasites: bicarbonate-dependent stimulation by pH in vitro.

Gametogenesis in Plasmodium gallinaceum involves bicarbonate-dependent processes and requires a continuous supply of glucose (presumably as an energy source). Emergence and exflagellation of gametocytes, in vitro, occur independently of the CO2 tension but are rigidly correlated with the pH of the external medium. In bicarbonate-saline gametogenesis is initiated only if the pH exceeds 7.7. Our results suggest that gamete development of malaria parasites is stimulated when infected blood is exposed to air because the decrease in the CO2 tension of the blood causes its pH to rise.

Animals↗
PubMed1978

Studies on enzyme variation in the murine malaria parasites Plasmodium berghei, P. yoelii, P. vinckei and P. chabaudi by starch gel electrophoresis.

Electrophoretic variation of the enzymes glucose phosphate isomerase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase and glutamate dehydrogenase (NADP-dependent) has been studied in the African murine malaria parasites Plasmodium berghei, P. yoelii, P. vinckei and P. chabaudi and their subspecies. Horizontal starch gel electrophoresis was used throughout. The number of isolates examined in each subspecies varied from 1 (P. y. nigeriensis) to 24 (P. c. chabaudi). Extensive enzyme variation was found among isolates of most of the subspecies from which more than two such isolates were available for study. It is clear that the phenomenon of enzyme polymorphism is of common occurrence among malaria parasites. With the exception of P. berghei and P. yoelii, of which all isolates share an identical electrophoretic form of lactate dehydrogenase, no enzyme forms are shared between any of the 4 species of murine plasmodia. By contrast, within each species common enzyme forms are shared among each of the subspecies. The subspecies are nevertheless, distinguished from each other by the electrophoretic forms of at least one enzyme. The distribution and reassortment of enzyme variation among isolates of a single subspecies is in accordance with the concept of malaria parasites as sexually reproducing organisms. The study of variation among parasites present in individual wild-caught rodent hosts demonstrates that natural malarial infections usually comprise genetically heterogeneous populations of parasites. Nevertheless, the number of genetically distinct types of parasite of any one species present in a single infected host appears to be small. Generally not more than 2 or 3 clones of parasite of distinct genetic constitution are present in a single infected animal.

Animals↗
PubMed1978

Morphometric and morphologic evaluation of pulmonary lesions in beagle dogs chronically exposed to high ambient levels of air pollutants.

Beagle dogs (104) comprising one control and seven treatment groups were exposed 16 hours daily for 68 months to filtered air, raw or photochemically reacted auto exhaust, oxides of sulfur or nitrogen, or their combinations. After a further 32 to 36 months in clean air, morphologic examination of lungs by light microscopy, scanning electron microscopy, and transmission electron microscopy revealed two important exposure-related lesions. They were enlargement of air spaces in proximal acinar regions, with and without increases in the number and size of interalveolar pores, and hyperplasia of nonciliated bronchiolar cells. Proximal enlargment of air spaces was most severe, both subjectively and morphometrically, in those dogs exposed to oxides of nitrogen, oxides of sulfur, or oxides of sulfur with photochemically reacted auto exhause. In contrast, hyperplasia of nonciliated bronchiolar cells was most severe in dogs exposed to raw auto exhaust alone or with oxides of sulfur. The air space enlargement and hyperplasia of bronchiolar epithelium correlated with functional impairment reported as occurring in these dogs. Foci of ciliary loss with and without squamous metaplasia were occasionally observed in trachea and bronchi. The observations indicate that enlargement of proximal acinar air spaces with some loss of interalveolar septa can develop in the absence of alveolar fenestrations. The persistnt nature of bronchiolar cell proliferations in such circumstances was also demonstrated. Two major toxicologic implications are (1) the production of permanent lung damage by much lower concentrations of pollutants than previously reported and (2) the apparent lack of additive or synergistic effects between oxidant gases and sulfur oxides.

Air Pollutants↗