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Biomedical subjects

P A Wallace

Publications and source records attributed to P A Wallace.

9 recordsLinked to original sources
PubMed2002

Efficacy of sex determination in the greater cane rat, Thryonomys swinderianus, Temminck.

The efficacy of the two most common techniques used for determining the sex of the greater cane rat, Thryonomys swinderianus, Temminck, was tested using 10 young and 8 adult animals with two technicians at the Animal Research Institute's Grasscutter Domestication Centre, Pokoase, Ghana. The techniques compared were the use of the head shape and/or head size and the use of the ano-genital distance. The use of the ano-genital distance for sex determination was validated in a colony of greater cane rats at various stages of development, i.e. from the day of birth to three or more years of age. The ano-genital distance was then used as the standard against which the use of the head shape and/or head size technique was tested. The results indicated that the use of the ano-genital distance for sex determination in the greater cane rat was error-free, even with little experience on the part of the practitioner. The ano-genital distance was more than twice as long in the males than in the females at all ages (p < 0.001). However, the use of the head shape and/or head size for sex determination was found to be associated with some degree of error in both sexes. The use of the ano-genital distance can therefore be recommended as an efficacious technique for sex determination in the greater cane rat.

Anal Canal↗
PubMed2000

Reproduction and mortality in a colony of captive greater cane rats, Thryonomys swinderianus, Temminck.

The reproductive performance and mortalities in a colony of captive greater cane rats, Thryonomys swinderianus, were monitored from 1992 to 1998 at the Grasscutter Domestication Centre, Achimota, Ghana. The animals were kept in cages and exposed to constant lighting from a 100 W electric light bulb during the night. The diet consisted mainly of freshly cut Panicum maximum (guinea grass) fed ad libitum, with occasional supplements of cassava and cane sugar. The results indicate that the mean litter size and litter weight were 2.9 +/- 0.51 and 439.4 +/- 81.23 g, respectively. These figures are low compared to those reported elsewhere. However, the mean birth weight was 151.2 +/- 11.08 g, higher by 12% than previously reported values. It is considered that poor nutrition, excessive exposure to light and stress were responsible for the relatively poor reproductive performance reported in these animals. The main causes of death were traumatic injuries (32%) and pulmonary congestion (16%).

Animal Husbandry↗
PubMed1998

Ring block for neonatal circumcision.

OBJECTIVE: To determine whether a difference in the behavioral and physiologic response to circumcision can be demonstrated between neonates undergoing the procedure with ring block and those receiving no anesthesia. METHODS: Forty healthy male newborns were assigned randomly to receive either ring block or no anesthesia. Indices of perceived pain including crying time, behavioral state, oxygen saturation, and heart and respiratory rates were recorded at baseline and at intervals during the circumcision. Infants were reassessed 2 minutes and 2 hours postoperatively. RESULTS: Infants receiving ring block cried less than did controls (P < .001). Anesthetized infants had smaller increases in heart rate (P < .005) and demonstrated less arousal (P < .005) during each operative interval. For all operative intervals combined, anesthetized infants had a smaller decrease in oxygen saturation (P < .001) and a smaller increase in respiratory rate (P = .005) than did controls. Two minutes postoperatively, anesthetized infants had returned to their baseline behavioral state, whereas controls remained significantly more aroused (P < .005). Two hours postoperatively, there were no significant differences in any variables between the groups, nor between each group and its baseline. There were no complications related to anesthesia administration. CONCLUSION: Neonatal circumcision causes behavioral and physiologic changes consistent with the perception of pain. Ring block is an effective method of anesthesia for this procedure.

Anesthetics, Local↗
PubMed1998

Effects of prophylactic antibiotics on endometrial flora in women with postcesarean endometritis.

OBJECTIVE: To determine the effect of prophylactic antibiotics on endometrial and endocervical microflora upon diagnosis of postcesarean endometritis. METHODS: The medical records of patients enrolled in open-label comparative trials of therapeutic antibiotics for postpartum endometritis between 1989 and 1994 were reviewed (n = 682). Endometritis was diagnosed by a standard definition that included fever and localizing signs. Endometrial cultures were obtained by a sheathed injection/aspiration technique. Aerobes and anaerobes were isolated by standard microbiologic techniques. The primary outcome, endometrial and endocervical microflora, was compared in women who received intravenous ampicillin (2 g every 6 hours for 1-3 doses), cephalosporin (2 g every 6 hours for 1-3 doses), or no prophylaxis. Secondary outcomes included the cure of endometritis and the prevalence of wound infection in the three groups. RESULTS: Four hundred sixty-five of 682 patients (67%) had a cesarean delivery. One hundred fifty-one patients received ampicillin prophylaxis, 100 patients received cefazolin prophylaxis, 18 patients received extended-spectrum antibiotics, and 196 patients received no prophylaxis. Patients who received cefazolin prophylaxis had a significant increase in enterococcus (P < .05) and a significant decrease in Proteus species (P < .05) from endometrial samples. Patients who received ampicillin prophylaxis had a significant increase of Mycoplasma species (P < .05), Klebsiella pneumoniae (P < .0001), Escherichia coli (P = .04), and any aerobic gram-negative rod (P = .003) from endometrial samples. Ampicillin prophylaxis was associated with a decrease in Prevotella bivia (P < .05) and any anaerobe (P < .01). Endometritis cure rates were similar between prophylaxis groups and between prophylaxis and treatment groups. However, the cefazolin prophylaxis followed by cephalosporin treatment was associated with more wound infections (19%) than other prophylaxis and treatment groups, (6%, P < .01). CONCLUSION: Ampicillin and cefazolin prophylaxis alters endometrial and endocervical microflora of women who develop endometritis. Whereas these changes had no effect on endometritis cure rate (power > 80%), the association between cefazolin prophylaxis followed by an extended-spectrum cephalosporin and wound infection may warrant caution against the use of the combination.

Adult↗
PubMed1996

Synthesis of racemic 2,4-dimethyltetradecanoic acid from Mycobacterium kansasii.

A known intermediate, (3 R, S; 5 R,S)-3,5-dimethyl-6-triphenylmethyloxyhexanal gave, in a Wittig reaction with 1-octyltriphenylphosphonium bromide and n-butyl lithium in anhydrous tetrahydrofuran, a mixture of olefininic compounds. Trityl deprotection and hydrogenation of the double bond afforded the (2 R, S; 4 R,S)-2,4-dimethyltetradecanols. Oxidation of the alcohol functionality using pyridinium dichromate in anhydrous N,N'-dimethylformamide gave racemic, (2 R, S; 4 R,S)-2,4-dimethyltetradecanoic acids, which were converted to their methyl esters. 2,4-Dimethyltetradecanoic acids are constituents of glycolipid antigens from Mycobacterium kansasii.

Mycobacterium↗
PubMed1994

Synthesis of 4,6:2',3':4',6'-tri-O-cyclohexylidene-alpha,alpha'-trehalose 2-palmitate: an intermediate for the synthesis of mycobacterial 2,3-di-O-acyl-alpha,alpha'-trehalose antigens.

The aim was to 'triprotect' trehalose by placing various acetals, or related protecting groups, across the 4,6-, 2',3'-, and 4',6'-positions, leaving the 2,3-positions free for subsequent acylation. Isopropylidene and ethylidene acetals were studied, with the formation of a small amount of 4,6:2',3':4',6'-tri-O-isopropylidene-alpha,alpha'-trehalose. 4,6:4',6'-Di-O-benzylidene-2',3'-O-(tetraphenyldisiloxane-1,3-d iyl)-alpha, alpha'-trehalose 2,3-diacetate was prepared in low yield. 1,1-Dimethoxycyclohexane reacted with methyl alpha-D-glucopyranoside to afford the 4,6-O-cyclohexylidene derivative, isolated as the diacetate; mild acid cleavage of the acetal gave the 2,3-diacetate. 4,6:2',3':4',6'-Tri-O-cyclohexylidene-alpha,alpha'-trehalose is the major product of the reaction between alpha,alpha'-trehalose and 1,1-dimethoxycyclohexane. 2,3:4,6:2',3':4',6'-Tetra-O-cyclohexylidene-, 4,6:4',6'-di-O-cyclohexylidene-, and 4,6-O-cyclohexylidene-alpha,alpha'-trehaloses were also isolated in lower yields, all acetals being characterised as their peracetates. The proportions of the different trehalose acetals were dependent upon the molar ratio of 1,1-dimethoxycyclohexane and particularly on the reaction temperature. The triprotected trehalose acetal was acylated with palmitic acid, with excellent regioselectivity, affording the 2-O-palmitoyl ester. This 2-monoacylated, triprotected trehalose is a key intermediate for the synthesis of 2,3-di-O-acyl-alpha,alpha'-trehalose glycolipid antigens, isolated from Mycobacterium fortuitum and Mycobacterium tuberculosis.

Acylation↗
PubMed1994

Synthesis of (R,S)-10-methyloctadecanoic acid (tuberculostearic acid) and key chiral 2-methyl branched intermediates.

Tuberculostearic acid, (R)-10-methyloctadecanoic acid, is a characteristic component of pathogenic mycobacteria and related organisms. Sensitive detection of this acid in infected material allows rapid detection of mycobacterial disease. A novel, convergent synthesis of tuberculostearic acid and key chiral intermediates is described in this communication, to provide a reference compound. Racemic and (R)- and (S)-1-iodo-2-methyldecanes were synthesised from 1-octanal and 1-carboethoxyethylidenetriphenylphosphorane as initial starting materials. 1-Hydroxyoct-7-yne was made from 1,6-hexanediol by two alternative methods and coupled with the above racemic iodide. Hydrogenation and oxidation of the resulting (R,S)-10-methyloctadec-7-yn-1-ol gave racemic tuberculostearic acid.

Oxidation-Reduction↗