Biomedical subjects
Publications and source records attributed to J M Gardner.
The process of credentialing and recredentialing providers in health plans is time-consuming and universally hated by doctors, but it is essential to maintaining the quality of the health care plan. It also can yield information about the quality of service provided in general by the network of physicians, as one IPA-model plan discovered.
The mouse pink-eyed cleft-palate (p(cp)) mutation is characterized by hypopigmentation associated with cleft palate, neurological disorders and runting. Most p(cp) homozygotes are born with cleft palate and die shortly after birth, presumably as a result of feeding problems. A few exceptional p(cp) mutants live beyond this stage but display tremor and jerky gait. We report here that the genes encoding the gamma-aminobutyric acid type A (GABAA) receptor subunits alpha 5 (originally described as alpha 4; ref. 4), beta 3 and gamma 3 are disrupted by a deletion in p(cp) mice. We also show that the alpha 5 and gamma 3 genes are located between the p and beta 3 genes on mouse chromosome 7. The p(cp) deletion leads to alterations of binding properties of the GABAA receptors in the brain, providing an in vivo model system for studying GABAA receptor function. The human homologue of the region deleted in p(cp) mice is associated with Angelman syndrome. Thus, p(cp) mice may be useful in defining the region containing the gene(s) for this syndrome.
We studied the uptake of Ca2+ in different intracellular Ca2+ pools by use of steady-state measurement of 45Ca2+ in a preparation of digitonin-permeabilized pancreatic acinar cells. The Ca2+ content of all intracellular pools was assessed at different free Ca2+ concentrations between 0.1 and 1 microM. At low Ca2+ concentrations, almost 50% of Ca2+ was taken up, ATP-dependent, in a non-mitochondrial pool. Even at 0.1 microM free Ca2+ the mitochondrial Ca2+ pool contained 26% (3.4 +/- 0.8 nmol Ca2+/mg prot) of the total Ca2+ and this percentage was increased to 49% at 1 microM Ca2+ (16.7 +/- 1.1 nmol Ca2+/mg prot). Our data also show that the uptake into the non-mitochondrial pool can be further differentiated on the basis of ATP-dependence, and that the ATP-independent uptake has a biphasic dependency on the free Ca2+ concentration.
The mouse pink-eyed unstable (p(un)) mutation, affecting coat color, exhibits one of the highest reported reversion frequencies of any mammalian mutation and is associated with a duplication of genomic DNA at the p locus. In this study, genomic clones containing the boundaries of the p(un) duplication were isolated and characterized. The structure of these sequences and their wild-type and revertant counterparts were analyzed by restriction mapping, PCR product analysis, DNA sequence analysis, and pulsed-field gel electrophoresis. DNA from p(un) was distinguished from wild-type and revertant DNA by a head-to-tail tandem duplication of approximately 70 kilobases. No differences were detected between revertant and wild-type DNAs. Thus, the reversion in phenotype of p(un) mice is coupled with the loss of one copy of an approximately 70-kilobase duplicated segment. Testable models are presented to account for p(un) reversion.
Complementary DNA clones from the pink-eyed dilution (p) locus of mouse chromosome 7 were isolated from murine melanoma and melanocyte libraries. The transcript from this gene is missing or altered in six independent mutant alleles of the p locus, suggesting that disruption of this gene results in the hypopigmentation phenotype that defines mutant p alleles. Characterization of the human homolog revealed that it is localized to human chromosome 15 at q11.2-q12, a region associated with Prader-Willi and Angelman syndromes, suggesting that altered expression of this gene may be responsible for the hypopigmentation phenotype exhibited by certain individuals with these disorders.
Recessive mutant alleles at the pink-eyed dilution (p) locus on mouse chromosome 7 reduce pigmentation of both the coat and eyes. Here we describe the properties and complementation interactions of 10 p alleles, including 6 not previously reported. Several alleles that cause additional phenotypes affecting development, reproduction, and behavior were shown to be deletions by using DNA probes derived from the p region. An alignment of functional and marker-defined units is proposed, giving a linear complementation map that orders at least four functional loci. The characterization of a nested set of deletions around p will facilitate detailed molecular analyses of the genes and developmental functions associated with this part of the mouse genome.
To assess whether cocaine exposure in utero affected adrenocortical responsiveness in the neonatal period, salivary cortisol levels were compared between noncocaine-exposed (n = 35) and cocaine-exposed (n = 11) healthy preterm infants just prior to hospital discharge. Cortisol levels were measured under three conditions: Basal--120 min after no disrupting event or behavioral distress; Noninvasive Stressor--30 min after a neurobehavioral examination; Invasive Stressor--30 min after a heel-stick procedure. There were no differences in Basal cortisol levels between the noncocaine-exposed and cocaine-exposed infants, but the cocaine-exposed infants had significantly lower levels in both the Noninvasive and Invasive Stressor conditions. The suppressed cortisol responding to stressful events in cocaine-exposed infants suggests that these infants may have decreased modulation capability to normally stressful events, which could underlie some of the subtle state regulation problems reported.
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It is generally believed that activity levels are reduced in poorly nourished children. This may conserve energy, but may have a detrimental effect on mental development. However there are few data which support this hypothesis. No previous studies were found which looked at the activity levels of stunted children. In this study we modified the time and motion observation methods of Torun (1984) by using recording periods of 1 instead of 10 min. This significantly reduced the estimated time spent by young children in moderate and vigorous activities. Four hours of observing young children while they were awake, using the modified method, produced highly reliable data. The activity levels of a subsample of children described in part I were observed. The children were aged 12-24 months and were observed for 4 h on 2 d. Seventy-eight stunted children (height less than -2 SD of median, NCHS) were compared with 26 non-stunted children (height greater than -1 SD). The stunted children were significantly less active than the non-stunted children, although the difference in activity rating was small (3.4 per cent). They spent more time in light activities (P less than 0.001) and less time in moderate or vigorous activities (P less than 0.01). Both groups slept a similar amount. Using Torun's values for the energy cost of activities it appears unlikely that the reduced activity would conserve energy to a great extent, but it may still be of biological importance, since it is comparable to the energy cost of growth at this age. Activity levels increased with age but were not significantly related to weight for height.(ABSTRACT TRUNCATED AT 250 WORDS)
In order to investigate possible contamination of saliva samples with formula or breast milk obtained from young infants for cortisol assays, we measured cortisol concentrations in 3 common infant milk formulas and in breast milk before and after defatting and extraction using a commercial radioimmunoassay kit. Cortisol concentrations obtained prior to defatting and extraction were equal to or higher than (1.64-82.80 micrograms/dL) levels reported for salivary cortisol levels reported in newborn infants (0.09-2.08 micrograms/dL). Cortisol concentrations obtained after the defatting and extraction were lower (0.02-0.15 micrograms/dL), indicating that values obtained prior to defatting and extraction were due to cross-reacting substances as well as cortisol. As saliva samples are not routinely defatted or extracted prior to being assayed, high cortisol levels and interfering substances in formula and breast milk could contaminate salivary cortisol measurements in young infants. The present study suggests that appropriate controls should be taken when making salivary cortisol measurements in young infants to help ensure accurate results.
Restriction fragments analysis of DNA from mouse-hamster somatic-cell hybrid clones revealed that a mouse gamma crystallin cDNA hybridized to genomic sequences located on mouse chromosome 1. Identification of restriction fragment length polymorphisms (RFLPs) in the gamma crystallin sequences of inbred strains of mice permitted the further localization of the gamma crystallin genes (Cryg) to the proximal region of chromosome 1 closely linked to the loci encoding isocitrate dehydrogenase (Idh-1), a low molecular weight (LM) crystallin protein polymorphism (Len-1), and fibronectin (Fn-1). A single recombinant was observed between Len-1 and an RFLP in the gamma crystallin gene family, consistent with the hypothesis that Len-1 is one of the several structural loci encoding gamma crystallin genes. Len-1 is probably located on the centromeric end of the Cryg gene family. Linkage of Idh-1, Cryg, and Fn-1 in mice extends the syntenic relationship of those loci to the human, bovine, and rodent genomes and may define a chromosomal region that is generally conserved among mammals. The map position of Cryg, near the eye lens obsolescence (Elo) locus, was confirmed by the discovery that the restriction fragment patterns of gamma crystallin sequences differed between strain C3H/HeJ and the congenic anophthalmic mutant strain, C3H.Elo. Therefore, the gamma crystallin genes were cotransferred with the mutant Elo gene in the derivation of C3H.Elo. The results establish that LEN-1 is a marker for the gamma crystallin gene family, position the gamma crystallin gene family relative to other markers on mouse chromosome 1, and provide additional evidence that the Elo mutation is encoded at a locus closely linked to the gamma crystallin gene cluster. This study found no evidence of recombination hot spots within the gamma crystallin gene cluster.
A laboratory fermenter was used to produce up to 12 l of infective Tolypocladium cylindrosporum blastoconidia in Sabouraud dextrose broth. Two media derived from coconuts were also demonstrated as suitable alternative systems for the production of viable blastoconidia. T. cylindrosporum conidia when dried at 37 degrees C and stored at 4 degrees C retained their viability for 10 months, but, when stored at 25 degrees C, the conidia lost viability after 2 months and blastoconidia did not survive the drying process. Distilled water suspensions were a simple, economic technique for the long-term storage of spores at both 4 and 25 degrees C. The adsorption of conidia onto silica gel crystals was a very suitable technique for the storage of stock culture material at 4 degrees C. The virulence, production and storage capabilities of both spore types were examined.
A blastoconidial preparation of the New Zealand isolate of T. cylindrosporum was tested in two field trials against larvae of the freshwater mosquito Aedes subalbirostris and the brackish water species Ae. australis. There was some reduction in the population of the Ae. subalbirostris larvae and larvae collected from the test pools exhibited signs of fungal infection when reared in the laboratory. In the brackish pools there was no observable decrease in the larval populations even though Ae. australis is the natural host of T. cylindrosporum [NZ]. Water volume fluctuations in the test pools were a major difficulty experienced when monitoring the results. Tests against field-collected non-target fauna indicated that T. cylindrosporum is non-specific in action. Species of daphnid, dixid larvae and copepods were all susceptible to infection at varying degrees.
Otorrhoea is a troublesome complication of middle ear ventilation tubes. This investigation of children with various ventilation tubes shows that the incidence of this complication varies with the type of tube used. In particular, Paparella type 2 tubes are associated with a higher rate of otorrhoea, and should be reserved for use when long-term ventilation is necessary.
The New Zealand strain of Tolypocladium cylindrosporum was cultured on Sabouraud dextrose agar medium under varying regimes of growth conditions. The isolate exhibited good tolerances to temperature (4-35 degrees C), pH (3-10) and salinity (0-7% NaCl). Optimal vegetative growth and sporulation were recorded between a temperature range of 20-30 degrees C, pH of 5-6 and a salinity level of 0-2% NaCl. The North American isolate of the fungus showed similar tolerances, while the European isolate was less tolerant.
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The New Zealand isolate of the entomopathogenic fungus Tolypocladium cylindrosporum was field-tested against larvae of the crab hole breeding mosquito Aedes polynesiensis. A reduction of approximately 87% was achieved in the larval populations of all crab holes treated with T. cylindrosporum by day 21 of spore application. However, the mosquito populations recovered to the pretreatment level within two months indicating that any residual activity of this pathogen was insignificant.
We report that the 12,000 dalton domain of fibronectin that interacts with fibroblast cell surfaces also binds specifically to thrombin-inducible, saturable receptors on platelets. Furthermore, we have used chemical cross-linking and monoclonal antibodies to show that the 12,000 dalton domain of fibronectin interacts directly with glycoprotein IIIa at the platelet cell surface. Both binding and cross-linking of this domain to platelets are competed by a hexapeptide previously shown to block fibroblast adhesion to fibronectin. Finally, we show that a complex of the platelet glycoproteins IIIa and IIb binds to affinity columns of a cell-attachment fragment of fibronectin. These results localize a major fibronectin-platelet interaction to a specific domain of fibronectin and to a specific platelet glycoprotein.