Influence of histamine and H1-receptor antagonists on ejaculated human spermatozoa: role of intrasperm Ca2+.

Histamine reduced sperm viability in a dose- and time-dependent manner, accompanied by rise in intrasperm Ca2+. Further, 2',4'-dichlorobenzamil hydrochloride (DBZ), a Na+-Ca2+ exchange inhibitor, known to elevate intrasperm Ca2+, potentiated both, elevation of intrasperm Ca2+ and spermicidal action of histamine. Pretreatment of sperm with very low doses of H1-receptor antagonists (chlorpheniramine, promethazine or diphenhydramine) prevented the histamine-induced elevation of intrasperm Ca2+ as well as its spermicidal action. However, pretreatment with famotidine, a H2-receptor antagonist did not produce such a protective action. The results strongly suggest that histamine elicits its spermicidal action via H1-receptors present on sperm cells.

Streptogramins: a new class of antibiotics.

Streptogramin antibiotics represent a unique class of antibacterials in the each member of the class consists of at least 2 structurally unrelated molecules: group a streptogramins (macrolactones) and group B streptogramins (cyclic hexadepsipeptides). Both group A and group B streptogramins inhibit protein synthesis at the ribosomal level, and they act synergistically against many isolates their combination generating bactericidal activities and reducing the possibility of emergencies of resistant strains. The mechanisms of acquired resistance to group B streptogramins remain unaffected by target modifications and active efflux. The pharmacokinetic parameters of group A and group B streptogramins in blood are quite similar. In addition, both the A and B group penetrate and accumulate in macrophages and in the bacterial gegetations of experimental endocarditis. Until recently, the complex and irregular composition of naturally occurring pristinamycin and virginiamycin, as well as the unavailability of soluble forms, have limited the clinical development of streptogramins. The synthesis of water soluble derivatives of pristinamycin IA and IIB has now allowed the development of injectable streptogramins with fixed compositions. This unique class of antibacterials will have a significant clinical impact in a world of increasing multidrug resistance affecting the Gram-positive cocci, especially staphylococci and pneumococci. The absence of cross-resistance to macrolides in many of these isolates and the rapid antibacterial killing against these species bright future for this class of antibiotics.

Opioid receptor mediated anticonvulsant effect of pentazocine.

Intraperitoneal (i.p.) administration of (+/-) pentazocine (10, 30 & 50 mg/kg), a Sigma opioid agonist, resulted in a dose dependent anticonvulsant action against maximal electroshock seizures in mice. This anticonvulsant effect of pentazocine was not antagonized by both the doses of naloxone (1 and 10 mg/kg) suggesting thereby that its anticonvulsant action is probably mediated by Sigma opiate binding sites. Its anticonvulsant effect was potentiated by both the anticonvulsant drugs viz. diazepam and diphenylhydantoin. Morphine, mu opioid agonist, on the other hand, failed to protect the animals against maximal electroshock seizures when it was given in doses of 10-40 mg/kg body wt.

Comparative study of out-reach immunization strategies in rural area.

Efficiency of out-reach immunization strategies operationalised in a rural area of district Ambala (Haryana) was evaluated. Till year 1984-85 immunization delivery was 'sporadic'. Annual cluster immunization campaigns were conducted during 1985-86 and 1986-87. This comprised of delivery of oral polio vaccine (OPV) and/or measles once in a year to all eligible children, other vaccine continued to be delivered by health workers during routine beats. Regular immunization sessions were undertaken in 1987-88 and 1988-89. All the vaccines were delivered on 4 fixed days (one day per week) of each month, covering village at least once a month. Significant increase in immunization coverage was observed after cluster campaigns. OPV increased from 46.5 to 73.6%, DPT from 49.1 to 75.5%, BCG from 48.7 to 72.2%, measles from 8.6 to 45.8% and tetanus toxoid (TT) for pregnant women (PW) from 41.8 to 65.3%. Under regular programme the coverage levels were maintained at OPV 79.4%, DPT 78.2%, BCG 70.6%, measles 48% and TT (PW) 76.2%. Regular out-reach immunization strategy was found to be better than cluster campaigns as it was 'regular' and high coverage level could be maintained.