V. Parthasarathy

Recombinant extracellular domains of tetraspanin proteins are potent inhibitors of the infection of macrophages by human immunodeficiency virus type 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection of human macrophages can be inhibited by antibodies which bind to the tetraspanin protein CD63, but not by antibodies that bind to other members of the tetraspanin family. This inhibitory response was limited to CCR5 (R5)-tropic virus and was only observed using macrophages, but not T cells. Here, we show that recombinant soluble forms of the large extracellular domain (EC2) of human tetraspanins CD9, CD63, CD81, and CD151 produced as fusion proteins with glutathione S-transferase (GST) can all potently and completely inhibit R5 HIV-1 infection of macrophages with 50% inhibitory concentration values of 0.11 to 1.2 nM. Infection of peripheral blood mononuclear cells could also be partly inhibited, although higher concentrations of EC2 proteins were required. Inhibition was largely coreceptor independent, as macrophage infections by virions pseudotyped with CXCR4 (X4)-tropic HIV-1 or vesicular stomatitis virus (VSV)-G glycoproteins were also inhibited, but was time dependent, since addition prior to or during, but not after, virus inoculation resulted in potent inhibition. Incubation with tetraspanins did not decrease CD4 or HIV-1 coreceptor expression but did block virion uptake. Colocalization of fluorescently labeled tetraspanin EC2 proteins and HIV-1 virions within, and with CD4 and CXCR4 at the cell surfaces of, macrophages could be detected, and internalized tetraspanin EC2 proteins were directed to vesicular compartments that contained internalized dextran and transferrin. Collectively, the data suggest that the mechanism of inhibition of HIV-1 infection by tetraspanins is at the step of virus entry, perhaps via interference with binding and/or the formation of CD4-coreceptor complexes within microdomains that are required for membrane fusion events.

Distinct roles for tetraspanins CD9, CD63 and CD81 in the formation of multinucleated giant cells

Members of the tetraspanin superfamily of proteins are implicated in a variety of complex cell processes including cell fusion. However, the contribution of individual tetraspanins to these processes has proved difficult to define. Here we report the use of recombinant extracellular regions of tetraspanins to investigate the role of specific members of this family in the fusion of monocytes to form multinucleated giant cells (MGC). In contrast to their positive requirement in sperm–egg fusion, previous studies using antibodies and knockout mice have indicated a negative regulatory role for tetraspanins CD9 and CD81 in this process. In an in vitro model of fusion using human monocytes, we have confirmed observations that antibodies to CD9 and CD81 enhance MGC formation; however, in contrast to previous investigations, we found that all members of a panel of antibodies to CD63 inhibited fusion. Moreover, recombinant proteins corresponding to the large extracellular domains (EC2s) of CD63 and CD9 inhibited MGC formation, whereas the EC2s of CD81 and CD151 had no effect. The potent inhibition of fusion and binding of labelled CD63 EC2 to monocytes under fusogenic conditions suggest a direct interaction with a membrane component required for fusion. Our findings indicate that the tetraspanins CD9, CD63 and CD81 are all involved in MGC formation, but play distinct roles.

Ethyl cellulose and polyethylene glycol-based sustained-release sparfloxacin chip: an alternative therapy for advanced periodontitis.

ABSTRACT This study reports the development of a sustained-release system of sparfloxacin for use in the treatment of periodontal disease. A sustained-release sparfloxacin device was formulated, based on ethyl cellulose (EC) 10 cps, polyethylene glycol (PEG) 4000, and diethyl phthalate (DEPh). It will hereafter be called the sparfloxacin chip (SRS chip). The chip has dimensions of 10 mm length, 2 mm width, and 0.5 mm thickness. The in vitro drug release pattern and clinical evaluation of the formulations were studied. Reports of the short-term clinical study show that the use of the SRS chip may cause complete eradication of the pathogenic bacteria in the periodontal pockets of patients who have chronic generalized periodontitis. In this clinical study, the baseline and follow-up measurements of various clinical indices, such as oral hygiene index(es), plaque index, sulcular depth component of periodontal disease index, gingival crevicular fluid flow measurement, and dark field microscopic examinations of oral pathogens in plaque samples were studied. Significant improvements were observed in many parameters of the treatment group compared with the placebo group.

Reduction of CD4 + CD25 + regulatory T-cells in migraine: Is migraine an autoimmune disorder?

Migraine is believed to be a chronic neurological disorder with the exact aetiology being unknown. But, there is a debate on the role of immune dysfunction in migraine pathophysiology. Hence, authors made a debut attempt to explore the link between lymphocyte subset populations and migraine. A significant increase in CD4(+) and decrease in CD8(+) population were observed in migraine patients compared to healthy volunteers. Interestingly, the immunoregulator CD4(+)CD25(+) levels were less in migraine patients compared to the healthy volunteers. The results of the present study indicate that failure of immunoregulation could be implicated in the pathophysiology of migraine.

Assessment of in vitro cytotoxicity and in vivo antitumor activity of Sphaeranthus amaranthoides burm.f.

Background: A number of plants have been used in Indian system of medicine such as ayurveda, unani and siddha, but most of these plants were not explored properly. Sphaeranthus amaranthoides (SA) Burm.f., is one such plant used as an energizer in siddha. Objective: To evaluate the anticancer effect of chloroform extract of the whole plant of SA Burm.f. against Ehrlich ascites carcinoma bearing Swiss albino mice. Materials and Methods: The anticancer effect of chloroform extract was investigated in Swiss albino mice bearing Ehrlich ascites carcinoma at two different dose levels. Acute toxicity studies were also performed to determine the safety of the extract. Mice injected with Ehrlich ascites carcinoma cells were treated with the extract of doses 200 and 400 mg/kg body weight and standard 5-fluorouracil 20 mg/kg body weight for 15 consecutive days. Animals were sacrificed on day 15 for determination of anticancer activity by evaluating tumor volume, nonviable and viable tumor cell count and hematological parameters. Results: Mice treated with the extract showed a significant decrease in tumor volume and viable cell count and an increase in nonviable cell count and mean survival time. The hematological parameters were also found to be restored to a normal level. Conclusion: The results indicate that the chloroform extract was producing anticancer activity comparable with that of the standard 5-fluorouracil.

Increased incidence of migraine in women correlates with obstetrics and gynaecological surgical procedures

Migraine is a common chronic neurological disorder; yet no possible aetiology has been identified so far. There is a debate that migraine worsens in women who undergo procedures such as hysterectomy, dilation and curettage (D&C) or cesarean section for delivery. Hence, the present study was attempted to explore the link between procedures like D&C, hysterectomy and cesarean section for delivery and the prevalence of migraine in women. A total of 185 migraine patients were screened based on the inclusion and exclusion criteria of the International Headache Classification guidelines and 70 females who satisfied the inclusion criteria were included for the study. Of the 70 female patients, the numbers of married and unmarried women were 47 and 27, respectively. About 36 married women (80%, 95% CI: 0.146-0.104) had undergone the procedures related to obstetrics and gynaecology as per their medical history. Interestingly, 12 patients (33%, 95% CI: 0.148-0.176) had not experienced migraine attack prior to the above mentioned surgeries. Although, the age adjusted incidence of diagnosed migraine per 100,000 populations showed higher risk between 16-20 years of age (95% CI: 0.104-0.121), significant risk (95% CI: 0.086-0.113) was also observed in the women of 31-35 years age group in the present study. Based on the present study, surgeries such as D&C, hysterectomy and cesarean section for delivery increased the prevalence of migraine in women. Therefore, such procedures should be avoided unless otherwise essential, particularly in patients with positive past history of migraine.

Characterisation of Streptomycetes from Lignite Mines and their Antagonistic Activity Against Bacteria and Fungi

It has been well established that microorganisms are virtually an unlimited source of natural products, many of which have potential therapeutic applications. Among the various organisms the filamentous soil bacteria of the genus Streptomyces are remarkable and are considered as a potential source of important bioactive compounds. In the present study we have isolated actinomycetes from six locations in Neyveli lignite mine area, Tamilnadu, India and tested for their antagonistic activity. Seven isolates, which possess good antagonistic activity against bacterial and fungal pathogens, were selected and all the isolates represented the genus Streptomyces. The isolates have been identified up to the species level as per ISP procedures. The results of the study prove that the lignite mines are very promising zone for potential actinomycetes.