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Biomedical subjects

J M Smith

Publications and source records attributed to J M Smith.

At least 325 records · Page 18Linked to original sources
PubMed1989

Nisoldipine inhibition of sodium influx into aorta from aldosterone-salt-hypertensive rats.

The purpose of this study was to determine whether increased sodium (Na) influx into the aorta was associated with aldosterone-salt hypertension in the rat and, if present, to determine what mechanisms contributed to the increase. Basal 24Na influx was elevated in aorta from the hypertensive rats (2.21 +/- 0.10 mmol/l cell H2O/min, n = 25) compared with control-salt rats (1.75 +/- 0.04 mmol/l cell H2O/min, n = 24). The calcium (Ca) antagonist nisoldipine inhibited the Na influx into aorta from hypertensive rats in a concentration-dependent manner. At 10 nM nisoldipine, the Na influx in hypertensive rats (1.52 +/- 0.14 mmol/l cell H2O/min, n = 10) was similar to control rats (1.66 +/- 0.18 mmol/l cell H2O/min, n = 7). The basal Na influx in aorta from hypertensive rats was not altered by dichlorobenzamil or ethylisopropylamiloride, selective inhibitors of Na-Ca and Na-H exchange, respectively. The Na influx was 2.21 +/- 0.10, 2.03 +/- 0.24, and 2.11 +/- 0.19 mmol/l cell H2O/min for basal (n = 25), dichlorobenzamil (n = 4), and ethylisoproisopropylamiloride (n = 11), respectively. Inhibition of Na influx in hypertensive rats by 0.1 microM nisoldipine (delta Na influx = -0.72 +/- 0.18 mmol/l cell H2O/min, n = 9) was not significantly altered when applied with dichlorobenzamil (-0.72 +/- 0.21 mmol/l cell H2O/min, n = 4) or ethylisopropylamiloride (-0.55 +/- 0.15 mmol/l cell H2O/min, n = 11). These agents did not alter Na influx in control aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1989

Social acceptance of mentally retarded children in regular schools in relation to years mainstreamed.

This study examined whether the social status of mainstreamed retarded children among their nonretarded peers improved as a consequence of extended contact. A sociometric questionnaire was administered to the nonretarded classmates of two groups of retarded children mainstreamed for an average of 1.7 yr. and 4 yr., respectively. Social acceptance of retarded children was low relative to their nonretarded peers. However, in contrast with previous research, retarded children did not receive higher social rejection ratings. Acceptance and rejection measures did not indicate any improvement in social status of the retarded children as a result of an extended period of mainstreaming.

Child↗
PubMed1989

Depression of hydrogen peroxide dependent killing of schistosomula in vitro by peritoneal exudate cells from Schistosoma mansoni infected mice.

Peritoneal exudate cells from mice infected with Schistosoma mansoni (S-PEC) can kill a small proportion of schistosomula in vitro in the presence of immune serum. S-PEC produce a low level of respiratory burst. However, schistosomula mortality in their presence is not reduced when exogenous antioxidants are added, suggesting that with S-PEC, oxidative killing may not be important. Hydrogen peroxide (H2O2) and superoxide production by S-PEC, and cells from Bacillus Calmette-Guerin (BCG) and thioglycollate (THGL) injected mice, nonspecifically stimulated with opsonized zymosan, were measured. Levels of H2O2 produced by S-PEC were significantly lower than BCG or THGL PEC, and were below the threshold for schistosomula killing. This correlated with lower levels of cell-mediated killing of schistosomula in vitro by S-PEC than by BCG-PEC. Superoxide levels, however, were similar between the 3 cell populations. It therefore appears that the efficiency of PEC to kill schistosomules in vitro correlates with H2O2 rather than superoxide levels. It was found that there was a sharp concentration threshold in H2O2 mediated killing of schistosomula. A depression in the levels of H2O2 produced may be a mechanism by which the parasite can partially evade the host immune system.

Animals↗
PubMed1989

Developing wellness programs: a nurse-managed Stay Well Center for senior citizens.

This article describes the process from conception to implementation of developing a nurse-managed wellness center for senior citizens. The center was established in a federally subsidized high rise residential complex in midtown Manhattan. The unique senior population living in this New York City community includes a large proportion of performing artists. These individuals are struggling to maintain ties to their community at a time when their most productive performing years have passed. A health needs assessment was designed to evaluate whether or not these seniors were interested and would participate in a nurse-managed wellness center. The strategies needed to propose and move the project forward through all systems are explored. Two clinical nurse specialists assessed the need, proposed the center, and guided it through several political systems while maintaining leadership to establish a viable and innovative hospital-based health center based on prevention.

Aged↗
PubMed1989

Leather.

Explore the source record for details and available documents.

Animals↗
PubMed1989

BRL 34915 (Cromakalim) stimulation of 42K efflux from rabbit arteries is modulated by calcium.

BRL 34915 (Cromakalim) is a novel benzopyran that has anti-hypertensive actions. Contractile and 42K efflux responses to BRL 34915 were measured in blood vessels from the rabbit to determine whether Ca-dependent K-channels [K(Ca)] were involved. BRL 34915 increased 42K efflux from all blood vessels tested with an EC50 of 0.2 to 0.7 microM in the superior mesenteric artery (SMA). BRL 34915 also inhibited norepinephrine (NE)-stimulated 42K efflux (96%) and contraction (50%) in SMA with IC50 values (0.2-0.3 microM) which were similar to the EC50. Comparison of two vascular sites showed that the portal mesenteric vein required 10-fold higher BRL 34915 to achieve a 42K response equivalent to the maximal effect on SMA, yet the maximum response to NE was 4-fold greater in portal vein than SMA. The 42K efflux stimulated by BRL 34915 exhibited a significant decrement with time. Ca-removal increased the magnitude and stability of the BRL 34915 response in SMA and femoral arteries, whereas reapplication of Ca in the presence of BRL 34915 caused the 42K efflux to decrease rapidly. These effects of Ca were not altered by nisoldipine (NIS). The 42K efflux stimulated by BRL 34915 and by K-depolarization was additive when applied in combination in SMA. BRL 34915 had no effect on the NIS-inhibited 42K efflux (a Ca-dependent component) during K-depolarization. It is concluded that BRL 34915 acts on K-channels which differ significantly from the known properties of K(Ca)-channels and that BRL 34915 indirectly inhibits NE stimulation of contraction and K(Ca)-channels by hyperpolarizing the smooth muscle membrane.

Animals↗
PubMed1988

Nucleotide sequence and analysis of the purA gene encoding adenylosuccinate synthetase of Escherichia coli K12.

Adenylosuccinate synthetase (EC 6.3.4.4), encoded by the purA gene of Escherichia coli K12, catalyzes the synthesis of adenylosuccinate (SAMP) from IMP, the first committed step in AMP biosynthesis. The E. coli K12 purA gene and flanking DNA was cloned by miniMu-mediated transduction, and the nucleotide sequence was determined. The mature SAMP synthetase subunit, as deduced from the DNA sequence, contains 427 amino acid residues and has a calculated Mr of 47,277. The size of the purA mRNA was determined by Northern blotting to be approximately 1.5 kilobase pairs. The 5'-end of the purA mRNA was identified by primer extension and is located 23 nucleotides upstream of the ATG translational initiation codon. Comparison of the purA control region with the guaBA control region revealed a common region of dyad symmetry which may suggest mutual elements of regulation. The purA control region did not resemble the control regions of the other known pur loci.

Adenylosuccinate Synthase↗
PubMed1988

The identity of Escherichia coli bacterioferritin and cytochrome b1.

Two different procedures were used to prepare pure samples of 'cytochrome b1' (column chromatography) and 'bacterioferritin' (immunoprecipitation) from Escherichia coli K-12 strain CA265. Both were crystallized, and X-ray-crystallographic data were compared with those from the bacterioferritin of E. coli strain W3300 used as a standard. We conclude that 'cytochrome b1' and 'bacterioferritin' are identical.

Bacterial Proteins↗
PubMed1988

Improved cat gene cassette for promoter analysis and genetic constructions.

A plasmid, pJS133, was constructed which contains a promoterless cat gene encoding chloramphenicol (Cm) acetyltransferase (CAT) conferring Cm resistance. This improved cat cassette, derived from the cat gene in plasmid pKK232-8 [Brosius, Gene 27 (1984) 151-160], offers several advantages over currently available cat cassettes. Expression of cat from this cassette reflects only transcriptional activity because of translational stops in all three reading frames, and possesses facile insertion/excision properties employing the flanking polylinker restriction sites. In plasmid pJS133, this cassette can be obtained by a single digestion with SmaI, HindIII, SalI, BamHI or PstI restriction enzymes. Additionally, 28 different cat cassettes with unique flanking restriction sites can be created by the appropriate double digestions.

Chloramphenicol O-Acetyltransferase↗
PubMed1988

Self-assembly of apoferritin from horse spleen after reversible chemical modification with 2,3-dimethylmaleic anhydride.

Apoferritin from horse spleen is composed of 24 subunits that undergo partial dissociation after chemical modification with 2,3-dimethylmaleic anhydride (DMMA), yielding dimeric, trimeric, and tetrameric intermediates, stable at pH 8.5 and 0 degrees C. Deacylation at neutral pH and elevated temperature provides a means to initiate reassembly by appropriate shifts of the solvent conditions. In order to monitor the pathway of self-assembly, starting from different intermediates of dissociation, dimers, trimers, and tetramers were isolated and investigated with respect to their capacity to accomplish reassociation. Intrinsic protein fluorescence, gel permeation chromatography, and analytical ultracentrifugation were applied to characterize the intermediate and final stages of association. The assembly of both the dimer and trimer yields greater than 85% of the native tetracosamer; the overall rate, starting from the dimer, exceeds the one starting from the trimer. Under comparable conditions, the tetramer exhibits only partial reassociation via the dimer and monomer; the corresponding dissociation reaction determines the observed slower rate. Significant assembly intermediates are "structured monomers", dimers, trimers, and dodecamers. Polymerization of the dimer via the tetramer, octamer, etc., does not occur on the pathway of assembly. The results confirm the assembly scheme proposed previously on the basis of cross-linking and spectroscopic experiments [Gerl, M., & Jaenicke, R. (1987) Eur. Biophys. J. 15, 103-109]. Comparison of structural models involving the different subunit interactions responsible for the sequential association supports the monomer----dimer----trimer----hexamer----dodecamer----tetracosamer mechanism of apoferritin self-assembly.

Animals↗