Hybrid between temperate phage P22 and virulent phage MB78

Bacteriophage MB78, a virulent phage of Salmonella typhimurium can not grow in rifampicin resistant mutant of the host. However, the temperate phage P22 which grows normally in this host helps MB78 to grow in its non-permissive host. P22 can not itself multiply under the condition of mixed infection and the burst size of MB78 is very much reduced. The burst sizes of both are reduced even when the permissive host LT2 is mixedly infected with P22 and MB78. When rifampicin resistant mutants are mixedly infected, only P22-specific mRNAs are produced in the early stage. This is followed by transcriptions from both P22 and MB78 genomes. Subsequently, only MB78-specific messengers are detected in the infected host. Hybrids between the two phages have been isolated from the mixedly infected cells. These hybrids which contain only 15-20% of P22 genome can grow in the rifampicin resistant mutants of the host. The analysis of hetero-duplex between MB78 and hybrid phages revealed the presence of at least three mismatch regions. Experiments are in progress to identify the parts of P22 genome present in the hybrid phage.

Bacteriophage P22 helps bacteriophage MB78 to overcome the transcription inhibition in rifampicin resistant mutant of Salmonella typhimurium

Bacteriophage MB78 cannot grow on rifampicin resistant mutant of host Salmonella typhimurium (rif39) which contains an altered beta subunit of RNA polymerase. Bacteriophage P22, however, grows normally in rif39 both in the presence or absence of rifampicin. Perhaps MB78 promoter is not recognized by altered RNA polymerase. As the phage P22 helps MB78 to grow to some extent on rif39, hybrids between P22 and MB78 have been isolated. Hybrid phage which can grow on rif39 contains mostly genes from MB78 although a small portion (15-20 per cent) of the genome belongs to P22 genome which helps MB78 to overcome the transcription inhibition in the host mutant with altered RNA polymerase.

Anti-inflammatory activity of amino acyl benzoates

Nineteen new piperazino or morpholino amino acyl benzoates were synthesized and screened against carrageenin induced oedema in albino rats. Several compounds of the series showed potent anti-inflammatory activity. Compound 10 was found to be the most potent. This compound was further evaluated in detail and compared with phenylbutazone for its relative anti-inflammatory potency and ulcerogenic liability. The compound, in addition, was compared with acetyl salicylic acid for its analgesic activity. This compound showed potent ant-inflammatory activity with minimal ulcerogenic liability.

First-dose and steady-state pharmacokinetics of valproic acid in children with seizures

The serum concentration-time curve of valproic acid was followed in 25 children after single oral doses of the drug and at steady-state. Total body clearance (CL), half-life (t 1/2), and apparent volume of distribution (Vd) were calculated from the terminal portion of the curve and from the area under the serum concentration-time curve (AUC). The CL and Vd were significantly greater at steady-state (0.42 +/- 0.20 ml/min/kg and 0.231 +/- 0.067 L/kg, respectively) than after a single dose (0.32 +/- 0.13 ml/min/kg and 0.191 +/- 0.055 L/kg, respectively). This difference was most pronounced in patients with valproic acid dosage increases in excess of 20% and no change in their concurrent anticonvulsant therapy between the single-dose and steady-state study periods. The t 1/2 was not significantly different between the 2 study periods. There was a significant correlation between age and both CL and Vd after single doses and at steady-state. The t 1/2 did not appear to be age related. These results suggest that the adequacy of the dosage regimen must be determined during maintenance therapy rather than extrapolated from data obtained after a single dose. Re-evaluation of therapy as the child grows older may also be necessary in view of the age-related differences in valproic acid pharmacokinetics which this study has demonstrated.

Thiolutin-resistant mutants of Salmonella typhimurium

Spontaneous mutants of Salmonella typhimurium isolated in our laboratory from thiolutin-containing tryptone agar plates are partially resistant to thiolutin in enriched media. In minimal media, they are not resistant. The mutants are not temperature sensitive but fail to support the development of phage P22 at higher temperatures (40 degrees C). Thiolutin did not interfere with RNA polymerase or nucleotide kinase in in vitro experiments. However, thiolutin did inhibit the rate of incorporation of exogenous uridine into the cellular pool and consequently the acid-precipitable material. It appears that one site of action of thiolutin is at the membrane level.

Participation of the host protein(s) in the morphogenesis of bacteriophage P22

Spontaneous mutants of S. typhimurium resistant to thiolutin are conditionally non-permissive for phage P22 development (Joshi and Chakravorty 1979). At 40 degree C non-infective phage particles are produced. Phage development in two nonpermissive hosts (18/MC4 and 153/MC4) has been studied in detail. The steps at which the phage morphogenesis is interfered with differ in the two mutants. The electron micrograph of the particles produced in the mutant 18/MC4 reveals the presence of normal-looking particles; these particles contain phage DNA, adsorb to the permissive host but fail to inject their DNA. The particles produced in the mutant 153/MC4 which fail to adsorb to the host are found to be tail fibre-less. These observations indicate the involvement of host protein(s) in phage P22 morphogenesis.

Simultaneous bilateral central dislocation of the hip--an unusual complication of eclampsia

Bilateral hip injuries are rare. A case of bilateral central dislocation of the hip caused by eclamptic convulsions is reported because of its rarity. Further, eclampsia as a cause of bilateral central dislocation has not been reported earlier. All the earlier 11 cases were due to therapeutic convulsions before 1960. The patient reported here was ambulatory 6 months after injury, with some restriction of rotation and abduction.

The forensic laboratory evaluation of evidence in alleged rape

Serial vaginal fluid samples were obtained for laboratory analysis in 15 couples after voluntary intercourse. These samples were analyzed to determine the rate of decay of sperm and prostatic acid phosphatase as it pertains to alleged rape. An attempt was made to identify the male partner by laboratory examination of pubic hair combings and for foreign ABO antigens in vaginal fluid. If consideration is given to proper laboratory controls, examination for spermatozoa and prostatic acid phosphatase remains the primary test in alleged rape.