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Biomedical subjects

M Brown

Publications and source records attributed to M Brown.

At least 631 records · Page 35Linked to original sources
PubMed1985

Immunologic memory to phosphorylcholine. VI. Heterogeneity in light chain gene expression.

BALB/c mice immunized with phosphorylcholine-conjugated keyhole limpet hemocyanin (PC-KLH) produce two types of anti-PC antibodies, designated group I and group II, which differ in their fine specificity and idiotype expression. Group II hybridomas can utilize VH genes and VL genes (in particular, V kappa 1-3) distinct from those expressed in the group I-like anti-PC myelomas. Here we have analyzed additional anti-PC hybridomas from BALB/c and (CBA/N X BALB/c)F1 male mice and also anti-PC antibodies purified from BALB/c and C57BL/6N antisera. Isoelectric focusing indicates that one of the group II hybridomas utilizes V kappa 1-3 and that related L chains are expressed in a major portion of group II serum antibodies. Other group II antibodies in antisera express different L chains, some of which are presently unidentified. However, isoelectric focusing analysis also indicates that the L chains of some group II hybridomas and serum antibodies are related to those found in the group I anti-PC myelomas and group I hybridoma and serum antibodies. In addition, one hybridoma was found to utilize lambda 2. Thus, it appears that the anti-PC antibodies with group II-like fine specificity can utilize a variety of VL genes related to, or distinct from, those expressed in group I antibodies.

Animals↗
PubMed1985

Schistosoma mansoni: degradation of host extracellular matrix by eggs and miracidia.

A radioactively labeled in vitro model of the extracellular matrix of the mammalian intestinal wall and of snail tissue was used to determine whether proteolytic enzymes released by eggs and miracidia of Schistosoma mansoni could degrade connective tissue macromolecules in the type of interactive framework found in vivo. Eggs were collected and miracidia hatched in the presence of antibiotics to eliminate bacterial contamination. Uninfected livers were used as controls to ensure that the tissue dissociation and egg collection procedures did not produce proteolytic activity. One thousand live eggs incubated with the extracellular matrix for 72 hr at 37 C degraded 31% of the glycoprotein in the matrix; there was no degradation of elastin or collagen. Medium conditioned by incubation with eggs degraded 60% as much of the matrix as the live eggs themselves. The proteolytic activity of the egg-conditioned medium was greater in the presence of dithiothreitol. Miracidia incubated with the extracellular matrix in tissue culture medium at 27 or 37 C rapidly transformed to living sporocysts. This transformation was accompanied by a release of proteolytic activity, resulting in the degradation of 49 to 58% of the glycoprotein in the extracellular matrix by 1000 miracidia. Again, no elastin or collagen was degraded. The time course of degradation by miracidia was rapid over 24 hr and thus similar to that previously reported for cercariae. Degradation by eggs occurred more slowly over 72 hr. These data confirm that both eggs and miracidia secrete proteinases which are capable of degrading at least the glycoprotein components of extracellular matrix to facilitate their migration through intestinal wall or penetration of snail tissue.

Animals↗
PubMed1985

Occupational allergy to the common house fly. (Musca domestica): use of immunologic response to identify atmospheric allergen.

A 48-year-old scientific worker developed rhinitis that occurred when she entered the housefly (Musca domestica) rearing room where she worked. She was found to have specific IgE antibody to M. domestica in her serum by RAST. She was relocated at work and avoided further occupational exposure to M. domestica. The level of specific IgE decreased in serial samples but subsequently increased after her inadvertent reexposure at work. Extracts of fly-cage dust and of high volume atmospheric samples from the fly-rearing room inhibited the M. domestica RAST in a dose-dependent fashion. After logit transformation the lines of inhibition of the fly cage dust and of the atmospheric samples were parallel and steeper than the self-inhibition by M. domestica, implying the cage dust and atmospheric samples shared antigens not present in the M. domestica extract. This method of monitoring atmospheric antigen has considerable potential for evaluating the effectiveness of environmental change in the workplace.

Air↗
PubMed1985

Molecular cloning of cDNA for human von Willebrand factor: authentication by a new method.

We have identified a 2.4 kb partial cDNA clone (pDL34) for human von Willebrand factor (vWf) mRNA. pDL34 was selected by screening an endothelial cell cDNA library with a radiolabeled reverse transcript of mRNA obtained by specific immunoisolation of vWf polysomes from endothelial cells. pDL34 selectively hybridized to an endothelial cell-associated 9.5 kb mRNA. To confirm its identity, SP6 RNA polymerase was used to generate in vitro transcripts of the cDNA. This synthetic RNA, truncated at its 5' end, directed the synthesis of several unique polypeptides in rabbit reticulocyte lysates. These polypeptides were immunoprecipitated by polyclonal and monoclonal anti-vWf antibodies. These results indicate that pDL34 contains an authentic partial copy of vWf mRNA. In vitro transcription of partial cDNA clones and translation of the resulting RNAs may be a useful general method of verifying the identity of various cDNA clones in circumstances where antibodies are available and protein sequence is not.

Antibodies, Monoclonal↗
PubMed1985

Peri-incisional mezlocillin versus rectal-metronidazole for wound infection prophylaxis.

One hundred and forty patients who underwent appendicectomy were included in a prospective randomized trial to compare the ability of preoperative rectal metronidazole and peri-incisional mezlocillin to prevent wound infection following appendicectomy. The results show that bactericidal local tissue levels of mezlocillin were uniformly achieved using the peri-incisional technique. The wound infection rate for the metronidazole group was found to be 15.9% and did not significantly differ from the wound infection rate when mezlocillin was used (10.4%). Peri-incisional mezlocillin therefore appears to be a viable prophylactic technique against wound infection following appendicectomy and may offer a cheaper alternative to intravenous intra-operative metronidazole administration in cases when pre-operative metronidazole suppositories have been omitted. The peri-incisional mezlocillin technique is also suitable for routine prophylaxis against wound infection following appendicectomy.

Adolescent↗
PubMed1985

The impact of deinstitutionalization on activities and skills of severely/profoundly mentally retarded multiply-handicapped adults.

This study evaluated the change in activity patterns and skills of severely/profoundly mentally retarded, multiply-handicapped residents as they moved from large total care institutions to community living. Twenty-seven individuals were evaluated just before leaving the institution, 3 months post-exit, and 9 months post-exit. In comparison to a nondisabled reference group, residents were less active, mobile, social, and independent both in the institution and community. Residents did show, however, significant changes toward the nondisabled pattern of daily living after moving to the community. Clients improved in 4 of 16 skill areas within 3 months after entering the community: expressive communication, eating, serving meals and washing dishes, and meal preparation.

Activities of Daily Living↗
PubMed1985

Intrauterine position affects sex-accessory biochemistry in adult female mice.

Female mouse fetuses that develop in utero implanted between two male fetuses (2M females) are shown as adults to have significantly elevated (P less than 0.01) levels of beta-glucuronidase activity in their preputial glands compared to that of OM females, females that had not been contiguous to males in utero, and 1M females, females contiguous in utero to only one male (mean +/- SEM, 2M females = 23,9 +/- 2.1, 1M females = 13.3 +/- 5.2, and OM females = 7.8 +/- 2.5 Modified Sigma Units/mg frozen weight). It is hypothesized that the increased enzymatic activity in the preputial glands of 2M females could be important in releasing steroid metabolites from voided urine. These metabolites could then act as pheromones and thus explain some of the described differences in sexual behavior correlated with intrauterine position.

Animals↗
PubMed1985

Content of K+ and Na+ in seminiferous tubule and rete testis fluids from Sertoli cell-enriched testes.

Seminiferous tubules of rats exposed to x-irradiation before birth were subjected to micropuncture in situ at 50 days of age to obtain samples of fluid 4 h after ligation of efferent ducts. The concentrations of cations in this fluid were: potassium, 39.7 +/- 1.2 mM, and sodium, 136.3 +/- 1.2 mM (means and standard errors, n = 5). Histologic examination revealed that germ cells constitute less than 1% of the cell population within the seminiferous tubules of these rats; the remaining cells were all Sertoli cells. Sertoli cells showed efflux of 86Rb+ with t1/2 of approximately 11 min and an active ATPase in plasma membranes. These activities were similar to those of Sertoli cells from normal rats. Germ cells from normal rats showed less rapid efflux of 86Rb+ (t1/2 greater than 60 min) and less active Na+/K+ ATPase in plasma membranes. It is concluded that Sertoli cells are responsible for the high concentration of potassium in seminiferous tubule fluid and that plasma membranes of these cells contain an active K+ pump that is not inhibited by ouabain (1 mM).

Animals↗
PubMed1985

The structure of adenovirus chromatin in infected cells.

The structure of adenovirus chromatin in infected cells was studied by micrococcal nuclease digestion and hybridization with virus-specific probes. In the early phase of infection (5 h) a significant proportion of viral molecules was organized like actively transcribed cellular chromatin. As expected for a transcriptionally active population of molecules, even at high multiplicity of infection the nucleosomal repeating pattern was less distinct than in a transformed cell which contained the corresponding but less active genomic region. The observed repeating pattern in infected cells was unlikely to be due to integrated molecules since less than 0.07% of input genomes became associated with cellular DNA. After the onset of viral DNA replication, the pool of viral chromatin organized like cellular chromatin rapidly increased. In addition, newly replicated molecules also maintained the cellular chromatin-like organization as measured by [3H]thymidine incorporation after the cessation of cellular DNA synthesis. These data suggest that newly replicated viral molecules are organized by histones into cell-like chromatin throughout the infection cycle. Coincident with the peak of viral DNA and core protein synthesis, and the decline of histone synthesis, the late, core-like non-repeating viral chromatin became dominant, increasingly obscuring the underlying repeating pattern. Experiments suggest that this late chromatin is destined for encapsidation, that the early chromatin persists and that viral core proteins do not displace histones on viral DNA. A model is proposed suggesting that transcription and type I replication occur on histone-condensed templates, while type II replication products late in infection are condensed by core proteins and are destined for encapsidation.

Adenoviruses, Human↗
PubMed1985

Tooth loss, attrition and temporomandibular joint changes in a Romano-British population.

Mandibular condyles and temporal fossae were studied in a large Romano-British collection of skulls. The size and shape of the condyles differed from those in previous populations studied. Changes in form or shape of the condyles were age-related and could be correlated to the number of teeth lost on the same side and on the contralateral side. No statistically significant correlations were seen between attrition and condylar form and surface change.

Adolescent↗