Detection of heterogeneous vancomycin-intermediate Staphylococcus aureus: A preliminary report from south India

Background & objectives: Although there are reports of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) across the globe, there is a lack of reliable data on hVISA in India. The present study was undertaken to determine the rate of hVISA among the methicillin-resistant Staphylococcus aureus (MRSA) isolates, and to compare the brain heart infusion agar with vancomycin 4 ?g/ml (BHIV4) method with population analysis profile-area under the curve (PAP-AUC) method for the detection of hVISA and to study the distribution of mobile genetic element that carries methicillin-resistance gene SCCmec (Staphylococcal cassette chromosome mec) types among these isolates. Methods: BHIV4 and PAP-AUC methods were employed to detect hVISA among 500 clinical isolates of MRSA. SCCmec typing of these isolates was performed by multiplex polymerase chain reaction. The clinical presentation, treatment with vancomycin and outcome was documented for patients with hVISA. Results: The rate of hVISA was 12.4 per cent by PAP-AUC method. Sensitivity, specificity, PPV, NPV and kappa agreement of BHIV4 with PAP-AUC was 58.06, 93.15, 54.55, 94.01 per cent and 0.498, respectively. The isolation of hVISA was significantly (P<0.01) higher in patients admitted to intensive care units and wards than in patients attending the outpatient departments. Only 38 per cent of the patients received vancomycin as therapy. Majority of the hVISA isolates carried SCCmec type V or IV. Interpretation & conclusions: The rate of hVISA isolation in our study was 12.4 per cent. The sensitivity of the BHIV4 screening test was low, and was in moderate agreement with PAP-AUC test. SCCmec type V was the predominant type seen in half of the isolates. More studies need to be done in different parts of the country on a large number of isolates to confirm our findings.

An immunohistochemical study of the gastrointestinal endocrine cells in the ddY mice

The distributions and frequencies of some endocrine cells in the gastrointestinal (GI) tract of ddY mice were studied with immunohistochemical method using 7 types of antisera against bovine chromogranin (BCG), serotonin, gastrin, cholecystokinin (CCK)-8, somatostatin, glucagon and human pancreatic polypeptide (HPP). All of 7 types of immunoreactive (IR) cells were identified. Most of IR cells in the intestinal portion were generally spherical or spindle in shape (open typed cell) while cells showing round in shape (close typed cell) were found in the intestinal gland and stomach regions occasionally. Their relative frequencies were varied according to each portion of GI tract. BCG-IR cells were demonstrated throughout whole GI tract except for the cecum and they were most predominant in the fundus and pylorus. Serotonin-IR cells were detected throughout whole GI tract and they were most predominant cell types in this species of mice. Gastrin-IR cells were restricted to the pylorus and CCK-8-IR cells were demonstrated in the pylorus, duodenum and jejunum with numerous frequencies in the pylorus. Somatostatin-IR cells were detected throughout whole GI tract except for the cecum and rectum and they showed more numerous frequencies in the stomach regions. In addition, glucagon-IR cells were restricted to the fundus, duodenum and jejunum with rare frequencies, and HPP-IR cells were restricted to the rectum only with rare frequency. In conclusion, some strain-dependent unique distributional patterns of gastrointestinal endocrine cells were found in GI tract of ddY mice.

Experimental Study on the Effects of Cabarmazepine on the Neurulation in Early Chick Embryos and Immunohistochemical Staining for Fibronectin

Teratogenic effects of carbamazepine, an anticonvulsant, on the neurulation of the explanted early chick embryos were studied utilizing the punched-out filter paper explantation and culture technique. Fresh fertilized white leghorn hen eggs were incubated for 20-30 hours in an egg incubator. The Hamburger and Hamilton stage 4-11 chick embryos were explanted using the punched-out filter paper explantation technique and cultured in the CO2 cell culture incubator for 6-10 hours. They were randomly divided into a control group and an experimental group. The experimental group was divided into five subgroups according to the carbamazepine concentrations of 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer with which the Ham's F-10 culture media were treated. The morphological characteristics and the incidences of teratogenic effects on the neurulation of early chick embryos in the control and experimental groups were compared with each other using the stereomicroscope and the electron microscope. The chick embryos of the same developmental stage were selected from the control and experimental groups, and immunohistochemical staining for fibronectin was done by the double-bridge PAP method. The results were as follows. 1) Of the 41 chick embryos cultured in the Ham's F-10 media without carbamazepine, 38 embryos(92.7%) developed normally, and 3 embryos(7.3%) developed abnormally. In contrast, among the 98 embryos cultured in the carbamazepine-treated media, 54 embryos(55.1%) developed abnormally. The frequent anomalous features were deformities of the neural folds, failure of neural tube closure, derangement of somites, and developmental arrest. 2) The frequency and severity of abnormal embryos increased in dose-dependent fashion. The embryos cultured in the media treated each with 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer of carbamazepine developed abnormally in 12.5%, 21.1%, 60.0%, 81.0%, 86.4% respectively. 3) The scanning electron microscopic findings in neuroepithelial cells of abnormally developed embryos were flattened and smooth cellular surface with diminished surface blebs and microvilli, and size irregularity of the cells. On transmission electron microscope, underdevelopment of intracellular microfilaments was seen, but there was no significant change in the intracellular organelle. 4) The immunohistochemical stainability of the extracellular fibronectin at the basal side of the neuroepithelium was decreased in the carbamazepine-treated embryos.

SUBSTANCE P-LIKE PROJECTIONS FROM THE MIDBRAIN RAPHE NUCLEI AND PERIAQUEDUCTAL GRAY TO THE THALAMIC VENTRAL POSTERIOR NUCLEUS IN THE RATS—A COMBINED STUDY OF HRP TRACING AND IMMUNOCYTOCHEMICAL METHOD / 解剖学报

The afferant projections and their chemical nature from the midbrain raphe nuclei and periaqueductal gray to the thalamic ventral posterior nucleus were st- udied by HRP retrograde tracing combined with PAP immunocytochemical method Following injections of HRP into the thalamic ventral posterior nucleus, and reactions by HRP and PAP were performed subsequently. The double labelling cells containing HRP-positive granules and substance P-like immunoreactivity were found in various areas of brain, that is, the contralateral principal sensory nucleus of trigeminal nerve,nucleus gracilis,nucleus cuneatus, bilateral ventrola- teral divisions of the periaqueductal gray and midbrain raphe nuclei.A comparison of cell counts of double labeled cells with the total HRP-labeled cells indicated that the cells observed in the dorsal raphe nuclei were 21?7 in each rat, which constituted 48% of total HRP-labeling cells; The double labeling neurons in nuclei raphe centralis superior were found in two cases only, the cell bodies were very sparse and distributed mainly in the caudal area of these nuclei The double labeling cells were detected in bilateral ventrolateral divisions of periaqu- eductal gray, predominantly ipsilaterally. The double labeling cells observed in each rat were 26?9 ipsilaterally and 11?4 contralateraIly. The numbers of double labeling cells were 38% of the total counts of HRP-labeling cells in each side. These results above indicate that the thalamic ventral posterior nucleus receives afferent projections from midbrain raphe nuclei and ventrolateral division of periaqueductal gray and in the pathway, a part of substance P-positive neurons are exhibited. Therefore, this study provides evidence for existance ascending projection of substance P-like immunoreactivity.