Influence of subchronic exposure to lindane on humoral immunity in mice

Lindane suppressed both primary and secondary antibody responses to sheep red blood cell (SRBC) in albino mice, the effects being more pronounced on the secondary than the primary response. However, a longer duration of pesticide exposure induced similar degrees of immunosuppression on both responses. The sequential study of plaque forming cells (PFC) kinetics revealed that suppression of plaque formation not only occurred at peak days but also on pre and post peak days, and there was no delay in peak antibody formation. Moreover, reduction in the primary PFC was not associated with decrease in the antibody response to SRBC. The results indicate that lindane suppresses both primary and secondary humoral immune responses in a time and dose dependent manner, and suggest a threshold susceptibility to exposure.     

Magnetic resonance imaging of the pelvic floor in the postpartum patient

Magnetic resonance imaging (MRI) was used to assess anatomical changes in the pelvic floor after childbirth. Six women underwent serial MRI examination within 30 hours and at 1 week, 2 weeks, 6 weeks and 6 months after delivery; 8 additional women were studied only within 30 hours of delivery. T-1 and T-2-weighted images of the pelvis in the transverse and sagittal planes with a 1.5-T MR imager were obtained. In the sagittal section we assessed the urethrovesical angle, urethral length, distance from the symphysis to the proximal and distal vagina, vaginal length, width and length of the sphincters, and the presence of sphincter defects. Axial sections were assessed for sphincter defects for the distance between the symphysis and midurethra, vagina and rectum. Only one parameter (distance between symphysis and distal vagina) changed significantly over time, without a clear trend in direction. Interobserver variation was reasonable (<15%) except for anal canal length, urethral length and distance between symphysis and anus. There were no significant correlations between birthweight and MRI parameters. There was a non-significant association (P = 0.09) between the sole combined sphincter defect and rectal injury, but not with episiotomy or parity. We concluded that it is feasible to determine multiple measurements on MR images to evaluate structures of the pelvic floor.     

The influence of early biological risk and the home environment on nine-year outcome of very low birth weight

The contributions of early medical risk and the early and contemporary home environment on cognitive and academic outcomes of 35 nine-year-old survivors of very low birth weight (VLBW) who were followed prospectively were investigated. There were no significant relationships between the measures of early medical risk and outcome. The quality of the home environment accounted for half of the variance in outcome. Five themes that showed consistent associations over time with positive outcomes were: parental responsivity, parent support for learning, parent involvement with the child, exposure to a variety of experiences, and the presence of a father figure.     

Oncogenicity testing of 2-ethylhexanol in Fischer 344 rats and B6C3F1 mice

An increasing number of studies, both experimental and epidemiologic, have provided evidence that filtering glaucoma surgery may be less effective than initially described. Of a number of risk factors for failure, duration and number of antiglaucoma drugs prior to surgery seem to play a critical role and highly accumulated antiglaucoma topical treatments significantly reduce success rates. Histopathological studies have confirmed that topically applied drugs may exert toxic effects to the corneoconjunctival surface, and induce chronic infraclinical inflammation, as shown by the presence of immune and inflammatory infiltrates in multitreated eyes. The origin of topical inflammation has not yet been clearly determined, but a common component of ophthalmic drugs, the benzalkonium chloride used as preservative in almost all antiglaucoma preparations, has shown strong evidence of toxicity. A number of questions remain to be investigated, but suppression of preservatives from chronically applied drugs should be a critical issue in the near future.     

Adrenal chromaffin cells on microcarriers exhibit enhanced long-term functional effects when implanted into the mammalian brain

Rat adrenal chromaffin cells attached to either collagen-coated dextran (Cytodex 3) or glass bead microcarriers, both of 90-200 microns diameter, were used as dopamine-secreting implants in the caudate-putamen of rats with 6-hydroxydopamine-induced unilateral lesions of the substantia nigra. As controls, beads without cells and cells in suspension alone were implanted. Chromaffin cells adhered to microcarriers reduced apomorphine-induced rotation by 75% in lesioned animals. Animals that were lesioned but not receiving cell implants or receiving beads alone showed no reduction. Animals implanted with cells not attached to beads also showed a reduction in rotation but this effect lasted less than three months. Microcarrier-attached cells, however, maintained their effect in reducing rotation for at least eight months (rotations were reduced from a control mean of 10.9 +/- 1.4 to 3.6 +/- 1.1 turns/min) without any "drop-off" of the effect. Histological examination showed that eight months post-implant the cells pre-adhered to beads were still present and could be stained by anti-tyrosine hydroxylase antibody. Sections stained with hematoxylin-eosin showed no signs of an inflammatory response. In contrast to beads implanted into the striatum, Cytodex bead implants injected into the lateral ventricle induced a histopathological response appearing to involve the ependyma and choroid plexus. Results suggest that the striatal parenchyma but not the ventricle is amenable to studies using the microcarrier approach to transplantation.     

Gram-negative anaerobic bacilli: Their role in infection and patterns of susceptibility to antimicrobial agents. II. Little-known Fusobacterium species and miscellaneous genera

Twenty infrequently reported species of gram-negative anaerobic bacilli other than Fusobacterium nucleatum, Fusobacterium necrophorum, and members of the genus Bacteroides were studied with regard to their role in infection and their susceptibility to antimicrobial agents. In addition, the literature regarding the recovery of these organisms from both the normal flora and infections of humans was reviewed. During a six-year period at the Wadsworth Clinical Anaerobic Bacteriology Research Laboratory (Veterans Administration Wadsworth Medical Center, Los Angeles, Calif.), 39 (6%) of 679 specimens obtained from anaerobic infections yielded "other gram-negative anaerobic bacilli" (OGNAB). Fusobacterium naviforme, Fusobacterium gonidiaformans, Fusobacterium varium, Fusobacterium mortiferum, and Fusobacterium russii were the most commonly isolated OGNAB. Most of the OGNAB tested were resistant to erythromycin, and most strains, except for F. varium, were susceptible to beta-lactam antibiotics and clindamycin. Chloramphenicol and metronidazole were active against all strains of OGNAB tested. Certain Fusobacterium species are undoubtedly previously unrecognized members of the normal flora of the oropharynx, upper respiratory tract, or urogenital tract and may be present in infections derived from these floras.     

Covalent interaction of [3H]-dopamine with rat brain proteins in vivo and with the dopamine-reuptake site of nerve endings in vitro

Isolated nerve endings have been demonstrated to undergo saturable, covalent interactions with [3H]-dopamine under physiological conditions; and the reaction is greatly accelerated by flash photolysis with ultraviolet light. With intact nerve endings, under conditions where dopamine reuptake occurs, benztropine and cocaine (inhibitors of dopamine reuptake), but not atropine or haloperidol (a postsynaptic antagonist), prevent the reaction. The reaction also occurs in vivo following the intraventricular administration of [3H]-dopamine, the reaction being greatest with mitochondria, followed by the nerve ending and myelin. With the use of sodium dodecylsulfate-gel electrophoresis, a number of proteins of varying molecular weight were labeled, and the pattern of labeling was similar in vitro and in vivo. One protein, with a MW of about 60,000 was labeled to an exceptionally high degree. A number of protein bands showed decreased radiolabeling in the presence of benztropine, a finding which suggests that they may be associated with the reuptake site. Both the addition of ascorbic acid and unlabeled dopamine inhibited the reactivity of [3H]-dopamine, and the effects were concentration dependent. In the absence of photolysis, the reaction (3H]-dopamine to synaptic membranes attained saturation within 10 min, but with photolysis and reaction continued at a constant rate even after 20 min. The results are discussed in relation to the use of [3H]-dopamine as a photoaffinity label of the dopamine reuptake site and in relation to the nature of the reactions with and without photolysis.