Biomedical subjects

Rashidul Haque

Publications and source records attributed to Rashidul Haque.

39 records · Page 3Linked to original sources

PubMed2002

Update on protozoan parasites of the intestine.

The last year has seen new approaches to the diagnosis, treatment, and prevention of protozoal infections of the gastrointestinal tract. Some of the news is not good: new foodborne and swimming pool outbreaks of cyclosporiasis and cryptosporidiosis, respectively, occurred in North America; paromomycin was shown to be ineffective treatment for cryptosporidiosis; and these parasitic diseases continued to have a worldwide impact on human health. On the bright side, there were important advances in the understanding of the pathogenesis of cryptosporidiosis and the diagnosis of amebiasis and giardiasis, and some new leads on the treatment of cryptosporidiosis and refractory giardiasis. Finally, evidence was found of acquired mucosal immunity to amebiasis in Bangladeshi children, offering a guide for the development of an amebiasis vaccine. This review is not intended to be comprehensive, but contains a variety of articles that the authors hope will be of interest to the reader.

Journal Article↗

PubMed2002

Retinal melatonin production: role of proteasomal proteolysis in circadian and photic control of arylalkylamine N-acetyltransferase.

PURPOSE: Dynamic day-night changes in melatonin synthesis are regulated by changes in the activity of serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AA-NAT]). Similarly, a light-induced decrease in AA-NAT activity at night rapidly suppresses melatonin synthesis. The purpose of the current study was to test the hypothesis that in vivo changes of AA-NAT activity in chicken retina homogenates parallel changes in AA-NAT protein. This led to examination of the role of proteasomal proteolysis in the regulation of retinal AA-NAT activity and protein levels. METHODS: Chickens, entrained to a 12-hour light-12-hour dark cycle, were assessed under various lighting conditions, in some cases after in vivo intravitreal administration of the protein synthesis inhibitor cycloheximide or lactacystin, an inhibitor of the 20S proteasome. Tissue homogenates were prepared, AA-NAT enzyme activity was measured, and immunoreactive protein was estimated by Western blot using an anti-chicken AA-NAT(1-21) serum. RESULTS: The abundance of AA-NAT protein in both the retina and pineal gland exhibited a daily rhythm that was statistically indistinguishable from that of AA-NAT's activity measured in tissue homogenates. Acute exposure to light at night rapidly decreased AA-NAT protein and activity in a parallel fashion. Administration of cycloheximide at night decreased retinal AA-NAT activity in darkness and enhanced the effect of light. The light-evoked suppression of retinal AA-NAT protein and activity was blocked by intravitreal injection of lactacystin, which also was found to increase AA-NAT activity, either at night or during the daytime. CONCLUSIONS: AA-NAT activity measured in tissue homogenates reflects the steady state level of enzyme protein. AA-NAT protein in the retina turns over rapidly, reflecting a balance of de novo synthesis and proteasomal proteolysis. The suppressive effects of light at night are due primarily to enhanced AA-NAT proteolysis.

Acetylcysteine↗

PubMedDate not supplied

Entamoeba histolytica: sequence conservation of the Gal/GalNAc lectin from clinical isolates.

The Gal/GalNAc lectin gene of Entamoeba histolytica is a major amebic virulence protein responsible for interaction with host tissues. We investigated sequence differences in the Gal/GalNAc lectin heavy subunit in three isolates from Bangladesh and one isolate from Georgia, each of which was determined to be genetically distinct by SREHP AluI digestion. Interestingly, we observed only slight genetic diversity in the lectin gene as compared with the HM1:IMSS laboratory strain, originally a clinical isolate from Mexico. Genetic conservation of the Gal/GalNAc lectin between isolates may reflect that the lectin is under strong functional selection or possibly, that E. histolytica is a clonal population. Sequence conservation of the lectin indicates that immune responses against it should be cross-protective.

Amino Acid Sequence↗