The relative contribution of antibody production and CD8+ T cell function to immune control of Trypanosoma cruzi

The life cycle of the protozoan parasite Trypanosoma cruzi in mammalian hosts includes both non-dividing trypomastigote forms which circulate in the blood and replicating intracellular amastigotes which reside within the cytoplasm of a variety of host cells. In this study we have used mice with induced mutations in genes responsible for either antibody production or cytolytic T lymphocyte (CTL) function to examine the relative contributions of these effector mechanisms to control of T. cruzi. Mice deficient in the production of antibodies exhibited a delay in the rise in acute phase parasitaemia and an extended time to death relative to mice lacking CD8⁺ T cells. Nevertheless, B cell deficient mice eventually succumbed to the infection. Prior infection with an avirulent strain of T. cruzi failed to protect either CD8⁺ T cell-deficient mice or B cell deficient mice from challenge infection with virulent parasites. In contrast, mice with disruptions in the genes controlling perforin- or granzyme B-mediated cytolytic pathways had parasitaemia and mortality rates similar to wild-type mice and were protected from secondary infection by prior exposure to avirulent parasites. These results 1) confirm that antibody production, although secondary in importance to cellular responses, is nevertheless absolutely required and 2) perforin- or granzyme B-mediated lytic pathways are not required for control of T. cruzi infection.     

Can mothers identify malnutrition in their children?

To assess mothers' perceptions about malnutrition and theirability to identify malnutrition in their own children, 339children aged 3–35 months and their mothers were studiedin two urban hospitals in Dhaka, Bangladesh, and in a communityclinic. The weight, height, and mid-upper arm circumferenceof the children were measured, and their mothers were interviewed.Child nutritional status according to their mother's statementand anthropometrically assessed nutritional status were compared.Sixty per cent of the mothers correctly identified better nutritionalstatus (weight/age >75% of NCHS median) and 67% mothers correctlyidentified malnutrition (weight/age < 75% of NCHS median)in their children. Sixty-one per cent of mothers with less than5 years of formal education correctly identified better nutrition(weight/age >75%) whereas 38% mothers with more than 5 yearsof education correctly identified better nutrition. Correctidentification of malnutrition was made by 70% of mothers withless than 5 years of formal education, and 74% of educated mothersdid the same. As regards causes of malnutrition, 33% of mothers stated thatlack of food at home resulted in undernutri-tion in their children(mean weight-for-age of these children was 65% of the NCHS median).Mothers' suggestions for improving child health were: betterfood in 31% cases; treatment of illnesses in 22% cases; andboth in 42% cases. The results suggest that most of the mothersare able to identify malnutrition in their children, and 95%of them are aware of ways to improve it, and that the provisionof adequate food and health care may improve child nutritionalstatus.     

Wegener's granulomatosis and acute upper limb digital ischemia

Wegener's granulomatosis is a rare disease which occasionally causes digital gangrene. We describe a patient who developed gangrene in an upper limb despite being on adequate treatment with intravenous cyclophosphamide and corticosteroids. Further management included administration of prostacyclin analogue (Iloprost) resulting in stabilization of disease.     

BILATERAL INCOMPLETE URETERIC DUPLICATION WITH A URETERIC DIVERTICULUM

A case of bilateral incomplete ureteric duplication with a ureteric diverticulum is presented. The aetiology of the latter and the possibility that the pain may be based on peristaltic dysfunction are discussed.     

Tinea capitis in Tripoli

Mycological examination of 600 cases of tinea capitis in Tripoli showed Trichophyton violaceum to be the most common isolate, followed by Microsporum canis, Trichophyton schoenleinii and Trichophyton mentagrophytes. The various clinical patterns which scalp ringworm may present is discussed and attention is drawn to the relatively common non-inflammatory seborrhoeic or dry scaly pattern.     

REVERSIBLE GELATION OF ARACHIN

Arachin forms a gel at acidic pH (pH < 3.8) which is thermolabile. The factors governing the gelation seem to be the concentration of the protein, heating temperature, heating interval, cooling temperature of the heated solution, pH, ionic strength and dielectric constant of the medium. Urea decreases gel strength. The cross-links involved in the gelation of arachin seem to be noncovalent in nature.     

EFFECTS OF CALCIUM ON NEUROMUSCULAR BLOCK BY SUXAMETHONIUM IN DOGS

The effects of intravenously administered calcium chloride onpartial neuromuscular block produced by small and large dosesof suxamethonium, tubocurarine and gallamine have been studiedin dogs. Calcium chloride brought about an improvement in twitchtension, and this depression lasted for 5–15 minutes.The possible mechanisms of the block produced by small dosesof suxamethonium. In the presence of a complete phase II blockproduced by suxamethonium, however, calcium chloride depressedthe twitch tension, and this depression lasted for 5—15minutes. The possible mechanism of the varying effects of calciumon different types of neuromuscular block are discussed andit is suggested that the depression of twitch by calcium inthe presence of desensitization block may be due to a "membranestabilizing action". It is possible that this observation mayprove useful clinically in differentiating desensitization blockfrom other varieties of neuromuscular block. ^*S.M.S. Medical College, Jaipur, India. ^*College of Medical Sciences, Banaras Hindu University,Varanasi, India