Amnioinfusion among women attempting vaginal birth after cesarean delivery.

Eighteen of 901 women (2%) attempting vaginal birth after cesarean delivery (VBAC) received amnioinfusion. No untoward effects occurred in the subjects or their fetuses. We conclude that, though amnioinfusion in the setting of a VBAC attempt is needed only infrequently, it appears to be a reasonable intrapartum management option. The usual safeguards for a VBAC attempt should be followed.

Unexplained displacement of ipsilateral ovary and fallopian tube.

During routine laparoscopy, the right fallopian tube and ovary were noted to be displaced. Ovarian and fallopian tube tissue were found on biopsy of adjacent omentum. The most probable cause is asymptomatic torsion of the right adnexum; therefore, evaluation of the renal system with intravenous pyelogram is probably not necessary.

Congenital depression of the fetal skull.

One hundred forty-seven cases of congenital skull depression are analyzed, including two presented by the authors, and a review of the literature follows. A management plan emphasizing a conservative approach is outlined.

Bone marrow and lymphocyte cytogenetics of rhesus monkeys (Macaca mulatta) treated with the clastogen Mitomycin C.

Rhesus monkeys (Macaca mulatta) were used to determine their effectiveness as experimental animals for different cytogenetic tests with mitomycin C (MC). The micronucleus test (MNT and/or chromosome analysis of blood and bone marrow were made before and/or after the treatment with mitomycin C. Thus, the controls data and treated data were obtained from the same animals. With the employed methology, the micronucleus test could not be performed on living animals. Less chromosomal damage was detected in the micronucleus test of post-mortem samples than in the chromosome analysis of bone marrow. No influence by the mutagen could be observed in lymphocyte chromosomes at any of the different times of analysis. In contrast to this, bone-marrow chromosomes seemed to be highly affected by mitomycin C at day 1, 2 and 3 after injection. However, before treatment and at day 14, 16 and 17 after treatment there was no visible increase in chromosomal aberration in bone marrow.

Rhesus monkey (Macaca mulatta) model in genetic toxicology mitomycin C clastogenicity in germ cells.

The value of rhesus monkeys (Macaca mulatta) as a genetic toxicology model is limited by their scarcity, expense, and impracticality of progeny testing. However, in some special circumstances, e.g., accidental exposure of humans to potential mutagens, rhesus monkeys or other primates may provide a superior animal model to help to cope with a difficult public health situation. Using the testis as a target organ we found that when primary spermatocytes were treated in pre-leptotene stage with 1 mg mitomycin C/kg body weight, the frequency of exchanges, fragments, sex-chromosome and autosomal univalents increased significantly at diakinesis-metaphase I. This response was absent in cells treated during diplotene, late pachytene or during spermatogonial stages. We suggested that animals should be evaluated not only for genetic toxicology parameters, but also toxicologically, histologically, behaviorally, for carcinogenesis and seminal cytology. Whenever possible, the animals should be recycled.

Opossums as a reservoir for Salmonellae.

Approximately 200 opossums, trapped during the fall of 1973 in the vicinity of Raleigh, NC, were maintained in the Institute's breeding colony in individual cages until the breeding season. Clinically normal, dead, and moribund opossums were examined for Salmonella. Six serotypes of Salmonella were identified in both clinically normal and diseased opossums. Positive culture results were obtained on 39 of 56 (70%) rectal swab specimens collected in the fall from incoming opossums, and on 30 of 50 (60%) rectal swab specimens collected during midwinter from an additional group of clinically normal opossums, which were maintained in isolation for approximately 3 months before testing. At necropsy, 87 of 108 (81%) diseased opossums were culture positive for Salmonella. Salmonellae in serogroups B and R were isolated from the spleen, liver, kidneys, or heart blood as well as the ileum of 57 diseased opossums. In 23 cases, S typhimurium or S bern was isolated in pure culture from the visceral organs. These findings indicated bacterial septicemia. In contrast, salmonellae in serogroups C1, E1, and F were routinely isolated from the feces of clinically normal and diseased opossums, suggesting a habitat restricted to the intestinal tract and probably the mesenteric lymph nodes. It was concluded that the opossum serves as a reservoir for a number of serotypes of Salmonella and may have an important role in the epizootiology of wildlife salmonellosis.

Perception of geometrical arrays tachistoscopically exposed in right and left visual fields.

Geometrical stimuli (48 6-item arrays of familiar forms, e.g., circle), tachistoscopically presented in the right or left visual field, were more accurately perceived in the right than left visual field by 15 college students. Targets about half the length of the displays exposed here were perceived with equal facility in both visual fields (Bryden, 1960). Results suggest that length of array might affect the difference in perceptual accuracy of forms shown in the right and left visual fields. Figures in the right visual field were predominantly processed from left to right, and forms in the left visual field from right to left. Since more symbols were identified in the right than left visual field, the left to right encoding sequence may be more efficient than a right to left movement. Limited experience of most Ss in reading symbols from left to right is probably only one factor. Extensive experience reading alphabetical material from left to right might have developed the physiological mechanism underpinning this sequence more than the one serving the opposite movement.

Methods for obtaining neonates of known age from the Virginia opossum (Didelphis marsupialis virginiana).

Postlactational estrus occurred in the opossum 6-17 da (mean 10.08 +/- 3.2da) after sucklings were removed from the pouch 1-60 da postpartum. This estrus occurred somewhat earlier in females whose young were removed later than 24 hr postpartum, rather than within the first 24 hr. Thirteen litters (37% conception) resulted from 35 initial attempts at breeding during postlactational estrus. Three of 5 females conceived when litters were removed twice in succession. The tendency forindividual females to bear large or small litters was sustained regardless of conventional or postlactational breeding. Continual rebreeding of the opossum after removal of nursing young may increase the yield of known age neonates for experimental purposes.

Renal agenesis in guinea pig and oppossum.

Complete absence of kidneys was observed in 3 neonatal guinea pigs which died 2-3 da after birth. Congestion of intestines and other organs was also observed. Renal agencies in the guinea pigs appeared to be of rare occurrence. Agenesis of right kidney was observed in 2 of over 500 opossums examined. Both opossums were males, and the corresponding ureters were smaller in diameter than the contralateral ureters. The left kidney was enlarged as a result of compensatory hypertrophy. The lumina of right ureters were found to be obliterated on microscopic examination.

Histopathologic changes in laboratory animals resulting from various methods of euthanasia.

The histopathologic changes caused by various methods of euthanosia were studied in rats, mice, guinea pigs, and rabbits. Lesions resulting from a particular methods of euthanasia were consistent from species to species. Each method studied affected the lungs to some degree, ranging from mild congestion of alveolar capillaries to marked intramural edema of pulmonary arteries and alteration of vascular permeability. Euthanasia of experimental animals by overexposure to CO2, or ip injection of concentrated sodium pentobarbital seemed most suitable for pulmonary studies. Decapitation (mice, rats, guinea pigs), cervical dislocation (mice), CO2, and intracardial injection of sodium pentobarbital were more suitable for examination of abdominal viscera.

Growth, kidney disease, and longevity of Syrian hamsters (Mesocricetus auratus) fed varying levels of protein.

Male and female hamsters were fed natural ingredient diets containing 6, 12, 18, or 24% protein. Differences in growth rate, feed consumption, kidney weight, serum chemistry (total protein, serum creatinine, blood urea nitrogen), and longevity were analyzed. The kidneys were examined microscopically and graded according to the severity of nephritis. The 6% protein diet resulted in the lowest frequency of nephritis, but the animals were significantly smaller and had shorter life spans than the remaining groups. The 12% protein diet initially promoted slower growth than 18 or 24% protein, but the differences in body weight eventually became insignificant. The 12% protein diet resulted in a higher frequency of nephritis than 6% protein, but lower than 18 or 24% protein. The 18 and 24% protein diets promoted the most rapid early growth as well as the highest frequency and most severe kidney lesions. Uremia did not appear to be a major cause of death. Longevity did not differ significantly among hamsters of either sex fed 12, 18, or 24% protein diets.

Vaginal septa in mice: incidence, inheritance, and effect on reproductive, performance.

Dorso-ventral vaginal septa were observed in 38% of the recently weaned BALB/cJ female mice in the production colony at The Jackson Laboratory. The frequency of septa in two other BALB/c substrains and eight different inbred strains ranged from 0 to 8%. The vaginal anomaly was similar regardless of genetic background although individual variations were observed. The remainder of the reproductive tract was normal. Microscopically, the septum consisted of a fibrous partition covered by normal epithelium. Genetic analysis was undertaken by outcrossing septate BALB/cJ females to C57BL/6J, DBA/2J, or BALB/cBy males. Examination of female F1 and F2 progeny indicated more than one recessive gene was involved and genetic background influenced expression of these genes. Reproductive performance of septate and nonseptate BALB/cJ females was compared using several criteria. Fewer septate females were fertile, but the fecundity of fertile septate females was not affected.

Comparison of tests for the diagnosis of spontaneous encephalitozoonosis in rabbits.

The effectiveness of immunofluorescence, complement fixation, microagglutination serologic tests, intradermal skin test, and detection of histologic lesions were compared for use in diagnosis of spontaneous encephalitozoonosis in rabbits. The India ink and microbead agglutination reactions were compared with immunofluorescence and complement fixation by testing 11 single or pooled sera. Serologic tests correlated best with each other and less well with intradermal tests or presence of lesions. Immunofluorescence, India ink reaction and microbead agglutination were equally useful in detecting antibodies to Encephalitozoon cuniculi. The intradermal test correlated best with the presence of detectable lesions.