Localization of actin in mammalian spermatozoa: a comparison of eight species

The distribution of monomeric and polymeric actin in spermatozoa from the bull, boar, rabbit, human, rat, mouse, golden hamster, and guinea pig has been examined by using a monoclonal antiactin antibody and NBD-phallacidin. Actin was present in sperm from each species. When the monoclonal antibody was used, there was a species-specific distribution and intensity of fluorescence, but no generalized pattern. Specific fluorescence was noted in the neck and principal piece of human sperm; in the postacrosomal region, neck, and midpiece of bull and boar sperm; in the postacrosomal region, neck, and principal/equatorial segment border of rabbit sperm; in the neck region of hamster sperm; and in the neck, midpiece, and principal piece of rat, mouse, and guinea pig sperm. Sperm from all eight species displayed no specific fluorescence with NBD-phallacidin, indicating that actin was present in a nonfilamentous form. SDS extracts of sperm were analyzed by SDS-PAGE and Western blotting; in sperm from each species, a 42-kD protein with specific affinity for the monoclonal antibody was present.     

The slide centrifuge gram stain as a urine screening method.

A slide centrifuge Gram stain procedure was performed to screen for bacteriuria 4161 urine specimens submitted in urine preservative tubes for routine culture. For slide centrifuge Gram staining, each urine sample was mixed well. Thereafter, 0.2 mL of each sample was placed, using a pipette, into a slide centrifuge chamber and centrifuged at 2,000 rpm for 5 minutes. The slides were heat fixed, Gram stained, and read by laboratory personnel who scanned 12 consecutive oil-immersion fields using a set pattern. The presence of the same organism in six or more fields was defined as a positive urine screen. Urine samples were cultured using a 0.001-mL loop and a comparison of culture growth with slide centrifuge screening was made. When growth of 100,000 or more colony-forming units per milliliter (CFU/mL) was the reference for comparison, the screen had a sensitivity rate of 98%, a specificity rate of 90%, a negative predictive value of 99%, and a positive predictive value of 65%. When a lower colony count of 10,000 or more CFU/mL was the reference for comparison, the screen had a sensitivity rate of 88%, a specificity rate of 95%, a negative predictive value of 96%, and a positive predictive value of 84%. The slide centrifuge Gram stain is a very sensitive screening method to detect bacteriuria in an adult male population.     

Evidence for platelet-activating factor as a late-phase mediator of chronic pancreatitis in the rat.

The role of platelet-activating factor (PAF) as a mediator of pancreatic inflammation was examined in the rat pancreatic duct ligation model of obstructive pancreatitis. Pancreatic generation of PAF, as measured by bioassay (ie, platelet [3H]serotonin secretion), was determined at various times after induction of inflammation. Tissue levels of PAF in the normal pancreas averaged 600 +/- 49 pg/g, but PAF was not detectable during the initial 24 hours of pancreatitis, a time when the inflammatory reaction would be considered acute, that is, during the period of maximal serum amylase release and the development of interstitial edema. However a substantial increase in pancreatic PAF levels (12 times control levels) was observed 7 to 14 days after duct ligation during the late-phase response interval similar to the situation characteristic of chronic pancreatitis in which parenchymal atrophy, fibrosis, and pancreatic insufficiency evolve. One week after duct ligation when PAF levels peaked, an evaluation was made of the effects of PAF antagonists (BN52021 and WEB2170) on pancreatic lesions using Evan's blue extravasation, pancreatic myeloperoxidase (MPO) activity, and acid phosphatase activity in peritoneal lavage fluid. BN52021 or WEB2170 treatment was shown to reduce pancreatic damage and inflammation significantly. Long-term in vivo administration of exogenous PAF (20 micrograms/kg/hr for 7 days) exhibited a reduction of [3H]thymidine uptake into and amylase release from pancreatic acini in vitro. Our observations 1) that pancreatic PAF levels increased significantly during the chronic phase of obstructive pancreatitis induced by duct ligation; 2) that inhibition of the action of PAF, through specific receptor antagonism, caused an attenuation of pancreatic lesions; and 3) that chronic administration of PAF resulted in decreased pancreatic regeneration and exocrine function are consistent with a pivotal role for PAF as a late-phase inflammatory mediator in chronic pancreatitis in rats.     

Intraocular grafting of cultured brain tissue: growth, vascularization and neuron survival in locus coeruleus and cortex cerebri

Locus coeruleus and cortex cerebri from embryonic (ED 17) and newborn rats were kept 4 days in tissue culture under conditions maintaining organotypic features and then transplanted to the anterior chamber of the eye of adult rats. Vascularization from the host iris was delayed in pre-cultured grafts as compared to directly grafted material. In spite of this, several morphological parameters developed normally. Thus, pre-cultured grafts grew considerably in oculo. Falck-Hillarp histochemistry showed that grafts of cortex cerebri received an adrenergic innervation from the host iris and that locus coeruleus grafts contained central adrenergic neurons capable of innervating a sympathetically denervated host iris. The successful combination of tissue culture and intraocular transplantation should permit the selective advantages of both techniques to be applied to the same tissue pieces, generating new information unobtainable by either method alone.     

Spatial distributions of cytoskeletal proteins and the nerve growth factor receptor in septal transplants in oculo: protection from abnormal immunoreactivity by hippocampal co-grafts.

Intraocular grafts of embryonic rat septum and co-grafts of septum plus hippocampus were studied with immunohistochemical markers after one and six months (short term) and 12 months (long term) of survival. Neurons in all the septal tissues expressed the epitope for the rat beta-nerve growth factor receptor in sections reacted with the monoclonal antibody 192-IgG. Stained fibers traversed the interface of the short and long term co-grafts and 192-IgG-positive processes were most prominent in the septum when combined with the hippocampal formation. In contrast, labeled processes were sparse and the perikarya of positive neurons appeared shrunken in the long term single septal transplants. Axon and dendrite profiles in the grafts were examined with antibodies that recognize the phosphorylated heavy neurofilament unit (RT97) and the high molecular weight microtubule-associated protein termed MAP 2, respectively. In the short term single and double grafts, characteristic arrays of RT97-positive processes defined the tissues and axonal tracts connecting the septum with the hippocampus. Typical immunostaining of the neuronal somas and the dendrite arbors were were outlined with the MAP 2 antibody. After one year in oculo, extensive changes in the patterns of axonal and dendritic immunoreactivity were noted in the isolated septal grafts. Abnormalities identified with the RT97 antibody included hypertrophied axons, short fragments of kinked axons and neurofilaments in the neuronal perikarya. The formation of circular "abnormal fiber aggregates" composed of densely packed abnormal and normal axonal processes were also distinctive in only the long term single septal transplants. In addition, a reduction in the density of dendrites and the presence of truncated arbors stained with the MAP 2 antibody suggested that regression of the dendrites had occurred. These spatial modifications in axonal and dendritic staining were not present in the septal portion of the combined preparations. In astrocytes, an increase in the antigenicity to glial fibrillary acidic protein paralleled the age of the transplant and was most extensive in the septal grafts. The results illustrate that intraocular co-grafts of hippocampus protect septal neurons and glial cells from abnormal changes in immunoreactivity to antibodies directed against cytoskeletal proteins and exemplify the long term supportive effects of the hippocampus on the morphology of septal neurons, including neurons that express the receptor for nerve growth factor.     

Use of transgenic animals for carcinogenicity testing: considerations and implications for risk assessment

Advances in genetic engineering have created opportunities for improved understanding of the molecular basis of carcinogenesis. Through selective introduction, activation, and inactivation of specific genes, investigators can produce mice of unique genotypes and phenotypes that afford insights into the events and mechanisms responsible for tumor formation. It has been suggested that such animals might be used for routine testing of chemicals to determine their carcinogenic potential because the animals may be mechanistically relevant for understanding and predicting the human response to exposure to the chemical being tested. Before transgenic and knockout mice can be used as an adjunct or alternative to the conventional 2-year rodent bioassay, information related to the animal line to be used, study design, and data analysis and interpretation must be carefully considered. Here, we identify and review such information relative to Tg.AC and rasH2 transgenic mice and p53+/- and XPA-/- knockout mice, all of which have been proposed for use in chemical carcinogenicity testing. In addition, the implications of findings of tumors in transgenic and knockout animals when exposed to chemicals is discussed in the context of human health risk assessment.     

Effect of Various Viruses on the Responsiveness of Mouse Lymphocytes to Phytohemagglutinin Stimulation

A comparison of viral-induced unresponsiveness of phytohemagglutinin (PHA)-induced deoxyribonucleic acid (DNA) synthesis of mouse lymphocytes was made by culturing the cells under identical conditions in the presence of HEPES buffer in a humid-air atmosphere. The degree of PHA-induced DNA synthesis was found to vary, depending upon the type of ribonucleic acid or DNA virus treatment. Myxovirus, paramyxoviruses, Mengo virus, leukemic viruses, herpesvirus, and vaccinia virus caused a depression in responsiveness, whereas lactic dehydrogenase virus, adenovirus, and polyoma virus induced an increase in DNA synthesis. Inhibition of DNA synthesis was significant only if the virus was added at 0 h or within the first 12 h after PHA stimulation. Time studies indicated that leukemic and nonleukemic viruses caused similar patterns in the alteration of PHA-induced DNA synthesis.