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Biomedical subjects

S Rao

Publications and source records attributed to S Rao.

At least 199 records · Page 11Linked to original sources
PubMed1997

A mucosal irritancy test device for intraoral use in dogs.

The objective of this investigation was to conduct, in dogs, a 6-hour acute mucosal irritation study of a new bioerodible treatment. The main problem was to retain the test drug in situ without extraneous irritation from the retention device. A buccal cup was machined from acrylic with a chamber capacity of 0.025 ml and a flange that could be ligated to a tooth. Ten female retired breeder beagles, 7 to 8 years old, with naturally occurring moderate periodontitis were examined and the upper canine teeth scaled to remove plaque and calculus. One week later the buccal cups were placed at the gingival margin of the upper canine teeth and fixed in place with wire ligature passing through holes in the flange and around the tooth, engaging shallow nicks made in the enamel near the gingival margin so the wire would not slide up and down. The buccal cup was further stabilized with glass ionomer cement placed on the crown and over the outer surface of the cup. Buccal cups were loaded with test, placebo, or no ointment by technicians in a scheme to which examiners were blind. Hourly examinations were made, and after 6 hours the cups were removed and gingival mucosa scored for irritation by a previously described method. All dogs tolerated the test and retained the cups for 6 hours. There was no mucosal irritation from the empty cups. We conclude that this new device can be used successfully for testing new agents for short-term mucosal irritancy.

Acrylic Resins↗
PubMed1997

Alpha 4 beta 7 integrin expression is associated with the leukemic evolution of human and murine T-cell lymphoblastic lymphomas.

We have previously shown that the in vivo coordinated expression of individual alpha 4 and beta 7 integrin chains correlated with the leukemic potential displayed by cell lines derived from murine lymphoblastic T-cell lymphomas (T-LBLs) when transplanted subcutaneously into syngeneic AKR mice. In the present study, by using immunofluorescence and immunocytochemical analyses, we have confirmed that the in vivo up-regulation of the alpha 4 beta 7 heterodimeric complex is associated with the leukemic behavior of AKR T-LBLs. In addition, when compared with the parental, highly leukemic NQ22 cells, the variant cell line NQ22V exhibited a reduced leukemic potential that was invariably associated with a delayed alpha 4 beta 7 up-regulation in vivo Moreover, the leukemic cell line SJ-1, derived from a spontaneous T-LBL of the SJL strain, also displayed high levels of alpha 4 beta 7 expression with a pattern of tissue distribution similar to that of NQ22 cells from leukemic AKR animals. Of note, in most of the tissues involved by murine T-LBL dissemination, and particularly in liver, kidney, and lung, alpha 4 beta 7-positive leukemic cells were always located around strongly VCAM-1-positive vascular spaces. These findings are consistent with a possible role of alpha 4 beta 7/VCAM-1 interactions in the extravasation and, consequently, in the leukemic dissemination of murine T-LBL cells. Immunocytochemical analysis carried out in 11 human T-LBLs showed that pathological lymph nodes from all 7 cases with bone marrow infiltration at presentation carried alpha 4 beta 7-positive cells, whereas all 4 aleukemic T-LBLs were repeatedly alpha 4 beta 7 negative, also in metachronous lesions. These findings suggest that alpha 4 beta 7-positive human T-LBLs may represent a distinct clinicopathological entity. In addition, alpha 4 beta 7 expression was significantly more prevalent in younger patients (< 11 years; P = 0.02), further supporting such a hypothesis. Moreover, as in murine T-LBLs, the pattern of alpha 4 beta 7 positivity in involved lymph nodes was mainly focal, whereas nearly all neoplastic cells infiltrating bone marrow expressed this integrin, suggesting a possible role for alpha 4 beta 7 in the leukemic dissemination also of human T-LBLs.

Adolescent↗
PubMed1997

Fish meal extract bile esculin agar (FMBE) a selective medium for Bacteroides fragilis group.

Fish meal extract bile esculin agar (FMBE) is prepared using Fish meal extract concentrate as the basal substance, for the selective isolation and presumptive identification of B.fragilis group. The efficiency of the medium was evaluated by growing stock cultures of B.fragilis groups as well as inoculating clinical specimens and comparing the results with Bacteroides bile esculin agar (BBE). All the 87 stock cultures of B.fragilis grew on FMBE and BBE. No other anaerobes tested grew on the medium. However 7 out of 65 neomycin resistant aerobes grew on the FMBE. From the 100 clinical samples, 62 strains of B. Fragilis group were recovered on FMBE and BBE, and 53 strains on supplemented BHIBA. The cost effectiveness, selectivity and the ability to detect esculin hydrolysis will enable FMBE as a suitable medium as comparable to that of BBE, if not superior.

Agar↗
PubMed1997

Sanitation for rural communities: first win the people's support.

A latrine project in an Indian village which failed because the inhabitants were scarcely brought into its planning and execution is contrasted with a moderately successful scheme in another village where a concerted effort was made to educate the community about the value of latrines and to obtain the people's participation.

Community Participation↗
PubMed1997

[Reconstruction of cervical stability following old facet dislocation of cervical spine].

A total of 12 cases of old facet dislocations of cervical spine treated between december 1988 and 1993 were analyzed in order to evaluate the efficacy of various surgical modalities. In this series, there were 8 males and 4 females, with ages ranged from 16 to 50 years old (averaged 37.8 years old). The duration from injury to admission to our hospital was ranged from 1 to 8 months (averaged 3.7 months). Dislocation levels were as follows: C3,4 in 1 case, C4,5 in 4 cases, C5,6 in 4 cases and C6,7 in 3 cases. Unilateral facet dislocation was in 7 cases and bilateral facet dislocation in 5 cases. Neurological status on admission was as follows: spinal cord and nerve root lesion in 5 cases, nerve root lesion alone in 5 cases and neurologically intact in 2 cases. Besides all facets receiving facetectomy and iliac bone graft, other four kinds of adjuvant treatments were used, including internal fixation by stainless wires laminae or spinous processes in 4 cases, Luque rod in 1 cases, anterior fibrolysis combined with posterior laminoplasty in 1 cases and sustained skull traction without internal fixation in 6 cases. The reduction efficacy from postoperative stustained skull traction was better and the stainless wires fixation ranked the next. The patients only suffering from the nerve root lesion recovered better, but those who had spinal cord combined with nerve root lesion recovered badly. In conclusion, for the treatment of old facet dislocation, it is necessary to resect the facet and graft with iliac bone.

Adolescent↗
PubMed1996

Inhibition of angiogenesis in human glioblastomas by chromosome 10 induction of thrombospondin-1.

Glioblastoma multiforme is distinguished from its less malignant astrocytoma precursors by intense angiogenesis and frequent loss of tumor suppressor genes on chromosome 10. Here we link these traits by showing that when a wild-type chromosome 10 was returned to any of three human glioblastoma cell lines U251, U87, or LG11, they lost their ability to form tumors in nude mice and switched to an antiangiogenic phenotype, as measured by the inhibition of capillary endothelial cell migration and of corneal neovascularization. This change in angiogenesis was directly due to the increased secretion of a potent inhibitor of angiogenesis, thrombospondin-1, because: (a) neutralizing thrombospondin completely relieved the inhibition; (b) the inhibitory activity of thrombospondin was not dependent on transforming growth factor beta; and (c) chromosome 10 introduction did not alter secreted inducing activity. The inducing activity was dependent on vascular endothelial cell growth factor and had an ED50 of 10 microg/ml in media conditioned by parental cells and 9-13 microg/ml in media conditioned by chromosome 10 revertants. Normal human astrocytes were also antiangiogenic due to secreted thrombospondin. The effect of chromosome 10 on thrombospondin production in vitro was reflected in patient material. Normal brain and lower grade astrocytomas known to retain chromosome 10 stained strongly for thrombospondin, but 12 of 13 glioblastomas, the majority of which lose chromosome 10, did not. These data indicate that the loss of tumor suppressors on chromosome 10 contributes to the aggressive malignancy of glioblastomas in part by releasing constraints on angiogenesis that are maintained by thrombospondin in lower grade tumors.

Animals↗
PubMed1996

Regulation of c-fos is affected by electromagnetic fields.

The goal of the present study was to determine if regulatory regions of the c-fos gene were responsive to electromagnetic field exposure. The research design used transfected cells to increase the sensitivity of assays designed to identify changes following exposure. HeLa cells were transiently transfected with plasmids containing upstream regulating regions of c-fos up to -700 base pairs, coupled with the prokaryotic reporter gene CAT. Cells were exposed to an environmentally relevant EMF of 60 Hz at 60 mGrms. CAT expression above control levels in transfected cells (region +42 to -700 bp) was observed following 5 min exposure to the electromagnetic field, with a peak at 20 min. The expression was at basal levels following 40 min exposure. Deletion analysis of upstream DNA narrowed the responsive region to 138 base pairs from -363 to -225, which contains the SRE/AP-1 sites.

Electromagnetic Fields↗
PubMed1996

Replication of O4-methylthymine-containing oligonucleotides: effect of 3' and 5' flanking bases on formation and extension of O4-methylthymine . guanine basepairs.

Four 25-mer oligonucleotides containing m4T(T*) with the 3'-->5' sequences A-T*-A, A-T*-C, G-T*-G and G-T*-C, together with four oligonucleotides containing the same sequences with unmodified T, were studied for the effect of the immediate 5' and 3' bases flanking m4T on in vitro replication. Under enzyme-limiting conditions, all m4T-containing oligomers showed a varying sequence-dependent blockage at the base 3' to m4T. However, with time and high concentrations of dNTP's, full replication beyond m4T did occur with Klenow fragment (Kf), although substantial blockage remained, particularly in the case when the sequence was 3'-A-T*-A-5'. The extent of blockage at the base 3' to m4T, compared to complete replication using Kf, followed the order A-T*-A > A-T*-C >> G-T*-C > or = G-T*-G. Two other DNA polymerases, HIV-RT and Sequenase, which, unlike Kf, do not have 3' proofreading activity differ, agreed with data obtained with Kf. We conclude that the extent of complete replication of m4T-containing oligomers is primarily a function of the 3' flanking base with a lesser effect of the 5' base and requires specific dGTP insertion opposite m4T. These data suggest that a 5' G . C pair favors the formation of the following T*-G and this latter step is rate-limiting. However, once a T*-G pair is formed, rapid elongation to full length transcripts occurs.

Autoradiography↗
PubMed1996

Ischemic colitis secondary to venous thrombosis. A rare presentation of cytomegalovirus vasculitis following renal transplantation.

Gastrointestinal complications occur after renal transplantation in up to 16% of patients. Cytomegalovirus (CMV) vasculitis can affect the gastrointestinal tract with significant manifestations, including colonic ulceration, bleeding, and perforation. We present a case of CMV vasculitis in a renal transplant patient that caused middle and left colic vein thrombosis and resultant ischemic colitis. There was no evidence of arterial involvement. To our knowledge, this is the first reported case of ischemic colitis secondary to large vein thrombosis associated with CMV infection.

Adult↗
PubMed1996

Characterisation of the double genome structure of modern sugarcane cultivars (Saccharum spp.) by molecular cytogenetics.

Cultivated sugarcane clones (Saccharum spp., 2n=100 to 130) are derived from complex interspecific hybridizations between the species S. officinarum and S. spontaneum. Using comparative genomic DNA in situ hybridization, we demonstrated that it is possible to distinguish the chromosomes contributed by these two species in an interspecific F1 hybrid and a cultivated clone, R570. In the interspecific F1 studied, we observed n + n transmission of the parental chromosomes instead of the peculiar 2n + n transmission usually described in such crosses. Among the chromosomes of cultivar R570 (2n = 107-115) about 10% were identified as originating from S. spontaneum and about 10% were identified as recombinant chromosomes between the two species S. officinarum and S. spontaneum. This demonstrated for the first time the occurrence of recombination between the chromosomes of these two species. The rDNA sites were located by in situ hybridization in these two species and the cultivar R570. This supported different basic chromosome numbers and chromosome structural differences between the two species and provided a first bridge between physical and genetical mapping in sugarcane.

Chromosome Mapping↗
PubMed1996

Inhibition by protease inhibitors of chemotaxis induced by elastin-derived peptides.

We studied the effect of two inhibitors of human neutrophil proteases on neutrophil chemotaxis induced by the hexapeptide Val-Gly-Val-Ala-Pro-Gly (VGVAPG), a recurring sequence in the elastin molecule. The inhibitors were tosyl-Phe chloromethyl ketone (TFCK) and N-methoxysuccinyl-Ala-Ala-Pro-Val chloromethyl ketone (MAAPVCK). We assayed chemotactic activity by the double-membrane technique in a modified Boyden chamber, after incubating the cells for 1 hr with varying concentrations of inhibitor. We observed a concentration-dependent inhibitory effect. We also measured the potency of the two chloromethyl ketones as protease inhibitors. The more potent protease inhibitor, MAAPVCK, was also the more effective in inhibiting VGVAPG-induced chemotaxis; its inhibitor dissociation constant was KI = 28 nM with elastase and KI = 33 nM with cathepsin G. For TFCK the corresponding KI values were 37 microM and 200 microM. The incubating concentration required to lower chemotaxis by half its uninhibited value was C0.5 = 0.64 microM for MAAPVCK, compared to C0.5 = 3.4 microM for TFCK. A third peptide, triglycinate (gly3), which did not inhibit the proteolytic activity of either elastase or cathepsin G, did not inhibit chemotaxis. Chemotaxis induced by formyl Met-Leu-Phe (fMLP) was weakly inhibited by both chloromethyl ketones with TFCK being somewhat more effective than MAAPVCK. We concluded that inhibition of VGVAPG-induced chemotaxis is in part specific, receptor mediated. We suggest that proteolytic inhibitors protect the extracellular matrix from degradation by inhibiting chemotaxis. Comparing the inhibitor concentrations required to half proteolytic activity with the concentration required to half chemotactic activity, we further suggest that the two functions may be of comparable significance.

Amino Acid Sequence↗
PubMed1996

Clinical outcomes assessment in multiple sclerosis.

This article represents initial deliberation of an international task force appointed by the US National Multiple Sclerosis Society to develop recommendations for optimal clinical assessment tools for multiple sclerosis clinical trials. Presented within this article are the key issues identified by the task force during its initial year of deliberation. These include the precise purpose for a clinical assessment tool, the clinical dimensions to be measured in a multidimensional outcome measure, desirable attributes of an optimal clinical outcome measure, the complexities of multidimensional outcome measures, the relative merits of categorical clinical ratings and quantitative functional assessments, and a number of other important design issues that relate to the use of a multidimensional outcome measure. An action plan for analysis of existing data is summarized, as are the plans for more detailed recommendations from the task force.

Clinical Trials as Topic↗
PubMed1996

Expression, purification, and characterization of the G domain of Saccharomyces cerevisiae elongation factor 2.

Protein synthesis elongation factor 2 (EF-2), a member of the G protein superfamily, catalyzes the movement of the ribosome along mRNA in a reaction driven by the hydrolysis of GTP. In the present study, we have expressed, purified, and characterized the G domain of Saccharomyces cerevisiae EF-2 to define its functional properties. A peptide of 185 amino acids was found to be sufficient to bind guanine nucleotides when expressed in Escherichia coli either as a fusion with the maltose binding protein or as a truncation. The fusion was expressed as a soluble, active protein, while the truncation was expressed as an insoluble protein that required renaturation in order to function. Similar to native EF-2, both expression products bound GDP, but they did so with significantly lower affinity (Kd ca. 200 microM for both the fusion and the truncation vs ca. 0.5 microM for native EF-2). However, in contrast to native EF-2 which requires the ribosome for GTP hydrolysis, the isolated G domain hydrolyzed GTP (Km ca. 40 microM; turnover rate ca. 0.5 min-1) in the absence of the ribosome. We conclude that the G domain residues necessary for GTP binding and hydrolysis are located in the first 185 amino acids of S. cerevisiae EF-2.

Cloning, Molecular↗
PubMed1996

Pitfalls in the surgical management of cervical spine injuries.

Records of 69 cervical spine injury patients referred to the authors' institution over a 3-year period were reviewed. The senior author documented "definite" and "probable" pitfalls occurring in the pre-, intra-, and postoperative management. Diagnosis, traction, bracing, surgical timing, intraoperative technical errors, and incorrect surgical decisions were noted. Of the 69 patients, 39 (56%) suffered a pitfall of management. Twenty-seven patients (39%) accumulated 49 "definite" pitfalls between them and 12 patients (17%) suffered a total of 20 "probable" pitfalls. Of the 49 definite pitfalls, 7 (14%) were preoperative, 17 (34%) were those of surgical decision making, 21 (43%) were operative, and 4 (9%) postoperative. Diagnostic errors and incorrect bracing and traction led to neurological worsening. Intraoperatively, technical errors (30%), wrong timing of surgery (24%), and incorrect choice of operation (16%) were the common pitfalls. Postoperative pitfalls consisted of inappropriate bracing (17%). A Cervical Spine Research Society review (1989) rated complications of cervical spine surgery at 6.3% (63/992). In this study, a sizeable portion (56%) of cervical spine injury patients requiring surgery were at a risk of complications. Short of complications, there are areas of management where errors may have less well-documented undesirable effects or increase the potential for morbidity. An awareness of these pitfalls and increased use of non-operative treatment may eliminate up to 73% of the pitfalls and thereby decrease the morbidity associated with the management of cervical spine injuries.

Adolescent↗
PubMed1996

1,N6-ethenoadenine and 3,N4-ethenocytosine are excised by separate human DNA glycosylases.

We previously reported our finding that human cells contain glycosylase activity toward all four etheno bases formed in DNA by chloroacetaldehyde and related bi-functional aldehydes. By enzyme purification, including FPLC, we isolated two separate glycosylase activities for 1,N6-ethenoadenine (epsilon A) and for 3,N4-ethenocytosine (epsilon C) respectively, from crude HeLa cell-free extracts, which also contained a number of well-described glycosylases. When Mono-S FPLC purified proteins were assayed against defined oligomers containing either epsilon A or epsilon C, it was found that epsilon A and epsilon C glycosylases were completely separated. It could also be demonstrated that each enzyme bound to and cut only epsilon A- or epsilon C-containing oligomers respectively. There was no overlap in specificity for these two substrates. Several other human glycosylase substrates were also tested and none were cleaved by epsilon C glycosylase. The epsilon C glycosylase activity identified in the present study apparently represents a previously unknown glycosylase. This work also suggests that enzyme recognition of closely related DNA adducts may depend upon subtle changes in local conformation.

Adenine↗
PubMed1996

Biological activity and clinical efficacy of intravenous high-dose thymopentin in metastatic melanoma patients.

Eight patients with cutaneous metastatic melanoma were submitted to high-dose intravenous thymopentin (TP5) treatment for 5 weeks: three patients received 1 g three times a week, three received 1 g daily and two received 2 g daily. Four out of eight patients presented a partial response of cutaneous lesions lasting for 1-7 months, and six remain alive with evidence of disease after a follow-up of 2-7 months. A remarkable histologic observation is the presence of tumour necrosis, which was seen as both single cells and large confluent areas. The majority of lymphoid cells present in the tumour are CD45RO+ and CD4+. The CD4+ cells might play an important role in the anti-tumour immune local response by secreting cytokines and inducing apoptotic and necrotic cell death. This hypothesis seems to be confirmed by the presence of a high number of CD4+ cells around intratumoral vessels, while the presence of endovascular micro-thrombosis provides indirect evidence of cytokine activity. Cellular lysis may be produced by the activity of both CD8+ and CD4+ lymphoid cells. The role of TP5 may be an activation of CD4+ and CD8+ lymphoid cells. Clinical and pathological data indicate that TP5 is able to produce consistent clinical and immunological effects in melanoma patients with cutaneous metastases.

Adjuvants, Immunologic↗
PubMed1996

Recurrent myelitis.

Three patients presented with acute complete transverse myelopathy which relapsed several times at the same site. These patients, two women and one man, had two to five attacks spanning three to seven years. All patients underwent detailed investigations including a complete myelogram and serial evoked potential studies. Oligoclonal bands were present in the CSF in one patient. Brain MRI was normal in two patients; MRI of the spinal cord was abnormal and showed cord oedema with multiple areas of hyperintense signals on T2 and proton density weighted scans and hypointense signals on T1 weighted images in areas corresponding to the clinical level, suggesting an inflammatory/demyelinating disorder. These patients may represent a relapsing demyelinating disorder restricted to the spinal cord, distinct from multiple sclerosis.

Adult↗