Interaction of Vibrio cholerae cells with beta-lactam antibiotics: emergence of resistant cells at a high frequency

Unlike other gram-negative enteric bacteria, Vibrio cholerae cells were equally susceptible to penicillin and ampicillin and in general more susceptible than Escherichia coli to most of the beta-lactam antibiotics. The turbidity of penicillin-treated cultures contained to increase exponentially for about 3 h, although the cell viability declined rapidly within 30 min of penicillin addition. Prolonged treatment with beta-lactam antibiotics produced cells resistant to these antibiotics. A fluctuation test indicated that this resistance might be due to adaptive mutation. Cells resistant to a beta-lactam exhibited broad cross-resistance to other beta-lactam antibiotics. A new 12,000-Da outer membrane protein was detected both in beta-lactam-resistant cells and in wild-type cells growing in medium containing beta-lactam antibiotics. While the penicillin-resistant cells had all of the penicillin-binding proteins (PBPs) present in the parental cells, significant differences in the relative proportion of low-molecular-weight PBPs were seen. The low-molecular-weight PBPs from resistant cells seemed to form more stable complexes with penicillin than those from the parental strain.

HIV antibody screening of commercially available blood products in India

In a screening of 182 vials of various commercially available blood products in the Indian market, 32 (17%) were found to contain HIV-1 antibodies. The contamination with HIV-1 antibodies was detected in all types of blood products including immunoglobulin preparations, cryoprecipitates as well as albumin. Interestingly, the contamination was seen almost exclusively in the products manufactured in the Bombay-Pune area (32 of 92, 34%). It was very low in products manufactured near Delhi (1 of 90). A single vial of imported Factor VIII concentrate tested negative.

Prenatal diagnosis of autosomal dominant microcephaly and postnatal evaluation with magnetic resonance imaging

A case of fetal autosomal dominant microcephaly was prenatally diagnosed with ultrasonography in a woman with previously undiagnosed microcephaly. At the time of initial ultrasonographic assessment, the mother was identified to have a markedly small cranium, consistent with maternal microcephaly. The ultrasonographic examination showed the fetal head size to be four standard deviations below the mean for gestational age. Gestational dating from the other biometric parameters and from the last menstrual period was consistent with 31 weeks' gestation. Neurosonographic evaluation of the fetus revealed no obvious structural abnormalities. Serial ultrasonographic examinations at 35 and 38 weeks' gestation showed no changes in the fetal head size. A 2.64 kg male fetus was delivered at term. Neonatal assessment showed the fetal head circumference to be less than the second percentile for gestational age. Neurologic assessment of the neonate with magnetic resonance imaging showed abnormal development of the brain, with small cerebellar and cerebral hemispheres, and pachygyria. These images are compared with the magnetic resonance images of the mother. Our findings of maternal and fetal microcephaly are consistent with autosomal dominant microcephaly. To our knowledge, this is the first report of the prenatal diagnosis of autosomal dominant microcephaly.

Bioeconomic dynamics of a fishery modeled as an S-system

A bioeconomic model of a single species fishery is developed by using a realistic catch-rate function and assuming that a regulatory agency controls exploitation of the fishery by imposing a suitable tax on the catch. The existence of a nontrivial steady state and its stability are examined. The optimal harvesting policy is discussed from the viewpoints of variational calculus and control theory. The fishery is then modeled as an S-system by following the recasting techniques of Savageau and Voit. Numerical examples of the optimal control curves and the yield-effort curves are obtained by executing the ESSYNS algorithm.

Morphological study of the combined effect of purpurin derivatives and light on transplantable rat bladder tumors

Purpurin derivatives, a group of synthetic photosensitizers, were tested for their photodynamic activity against transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide-induced urothelial tumors growing in male Fischer 344 rats. Histological examination of tumors in animals treated with the purpurin derivatives and red light (greater than 590 nm, 360 joules/cm2) revealed tumor cell necrosis 24 h after completion of therapy. Control tumors showed no histological change. Purpurins have a major absorption peak in the red region (greater than 650 nm) of the visible spectrum, a region with good tissue penetration, and purpurins can be synthesized with a high degree of purity. This study demonstrates the potential of purpurin derivatives as photosensitizers for photodynamic cancer therapy.

Photodynamic treatment of transplantable bladder tumors in rodents after pretreatment with chloroaluminum tetrasulfophthalocyanine

Chloroaluminum tetrasulfophthalocyanine (AlPCS) was used as a photosensitizer for the photodynamic treatment of transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) induced urothelial tumors. Two groups of six rats each were injected with AlPCS (three micrograms./gm. body weight) and 24 hours after injection underwent photodynamic treatment with red light (greater than 590 nm., 360 joules/cm.2). Tumors examined four hours (Group I) and 24 hours (Group II) after the completion of phototreatment showed extensive hemorrhagic necrosis. Tumors treated with AlPCS alone showed no changes. In two other groups of six rats each, blood flow to tumors treated with AlPCS alone (Group III) and AlPCS plus light (Group IV) was measured using the radioactive microsphere technique. AlPCS plus light resulted in a significant decrease (p less than .05) in tumor blood flow within 10 minutes of completion of phototreatment while AlPCS alone had no effect on tumor blood flow. These findings are similar to those observed when higher doses (10 micrograms./gm. to 20 micrograms./gm. body weight) of hematophorphyrin derivative (HpD) and light were used for phototreatment of FANFT induced tumors. AlPCS is a stable sulfonated derivative of tetraazotetrabenzoporphyrin which absorbs maximally in the red portion of the visible spectrum, a region with good tissue penetration properties. These studies suggest the AlPCS may be a useful new agent for photodynamic therapy of cancer.

Histological study of the effect of hematoporphyrin derivative photodynamic therapy on the rat jejunum

Hematoporphyrin derivative photodynamic therapy is evolving as a local treatment for neoplastic disease. The emphasis of previous research has been on the determination of mechanisms of tumoricidal activity and defining the tumoricidal porphyrin component in hematoporphyrin derivative. The effect of hematoporphyrin derivative photodynamic therapy on normal tissue has received little attention. In the following study we examined the morphological changes of normal rat intestine exposed to hematoporphyrin derivative and light. In this model a segment of rat jejunum was exposed to red light (greater than 590 nm; 360 J/cm2) 24 or 72 h after the i.v. administration of hematoporphyrin derivative (5 or 10 micrograms/g body weight). Control groups received either no treatment, hematoporphyrin derivative only, or light only. Four h after treatment, intestinal segments were removed and examined by light microscopy. Segments treated with hematoporphyrin derivative and light showed extensive sloughing of the mucosa and submucosa with sparing of the muscular and serosal layers. It appears that hematoporphyrin derivative photodynamic therapy is capable of causing mucosal and submucosal damage to normal rat jejunum at these doses of light and hematoporphyrin derivative.

Structural polypeptides of cholera bacteriophage phi 2

The structural polypeptides of the cholera bacteriophage phi 2 have been analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Eight different polypeptides were identified. The apparent molecular weights of the polypeptides were 143 000, 96 500, 68 000, 53 000, 37 500, 29 500, 21 000, and 13 500, respectively. The percentage of total protein corresponding to each polypeptide was estimated.

Spectrophotometric characteristics of cholera phage phi2 DNA

Purified preparations of cholera bacteriophage phi2 were treated with cold phenol and the nucleic acid examined for its hydroxyapatite chromatographic pattern, thermal denaturation profile, base composition and mol. wt.