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Biomedical subjects

R White

Publications and source records attributed to R White.

At least 649 records · Page 36Linked to original sources
PubMed1985

Microbiology teaching in American dental schools.

A comprehensive questionnaire on current practices relevant to teaching microbiology to dental students was sent to all dental schools in the United States. The survey collected information on resources available, modes of teaching, and evaluation processes. Seventy percent (42/60) of the schools responded. Great variation was found in the teaching of microbiology largely due to the variety of educational resources, perspective of subject matter by the faculty, and the backgrounds of entering students. Data are presented that document the integration of microbiology with other courses, placement of microbiology in the curriculum, class attendance policies, availability of advanced selective and/or elective courses, and National Board reviews. These and other data indicate some prevailing trends in the teaching of microbiology to dental students.

Curriculum↗
PubMed1985

An ultrastructural study of lesions induced in the cerebellum of mice by inhalation exposure to methyl chloride.

Female C57BL/6 mice were exposed for 6 h/day, 5 day/wk for 2 weeks, to 1,500 ppm methyl chloride. Focal and diffuse malacia, involving the cerebellar inner granular layer was found while renal lesions were minimal or absent. The cerebellar lesions were most frequently found in the ventral paraflocculus, and less often in other regions of the cerebellum. The earliest ultrastructural changes were seen in the nuclei of scattered cerebellar granule cells, with progression from slight confluence of heterochromatin, to complete nuclear condensation or karyorrhexis. More severely affected areas exhibited severe watery swelling and disruption of granule cell perikarya with less severe changes in other cell types. Blood vessels appeared normal, even in areas of severe malacia. It was concluded that the lesions in the mouse cerebellum closely resemble methyl chloride induced brain lesions previously described in guinea pigs, and that these lesions are not secondary to the renal toxicity of methyl chloride.

Air Pollutants↗
PubMed1985

Three years' experience with an intestinal failure unit.

The work of a purpose-built unit for the treatment of intestinal failure is described. In the 3 years following its opening the 4-bed unit treated 83 patients who were admitted for a mean of 35 days. Major indications for admission were difficult cases of Crohn's disease, intestinal fistulae and short bowel syndrome. Since the unit opened the mortality rate in this type of patient has fallen from 42% to 20%. The principal treatment used was total parenteral nutrition (TPN) although 52 of the 83 patients also required major surgery. Repeated experience with the same type of clinical problem has led to more efficient patient management and has reduced the complication rate associated with TPN. The unit has acted as a centre for the management of patients needing Home Parenteral Nutrition and has an active role in training nursing and medical staff in intravenous therapy. A plea is made for the establishment of regional intestinal failure units.

Adolescent↗
PubMed1984

A second type II restriction endonuclease from Thermus aquaticus with an unusual sequence specificity.

A type II restriction endonuclease activity free of TaqI was prepared from Thermus Aquaticus YT. The fraction contains two endonucleolytic components with apparently different specificities, however the major activity is sufficiently dominant to allow partial digestion analysis of the position of recognition sites. A precise determination of the location of cleavage sites in pBR322 DNA and a computer-aided search for regions of homology in the vicinity of the cut sites indicate that this enzyme recognizes the nonpalindromic sequences GACCGA or CACCCA. Other related sequences are not cleaved, in particular, GACCCA and CACCGA, indicating that the enzyme requires the identity of nucleotides in the first and fifth positions, a type of specificity that has not been previously reported. The position of cleavage is located outside of the site and is represented as: (Formula: see text).

Base Sequence↗
PubMed1984

Homozygosity of chromosome 13 in retinoblastoma.

We studied the frequency of chromosome 13 homozygosity in tumor tissue obtained directly from eyes harboring retinoblastomas. The data indicate that approximately half of all retinoblastomas are homozygous for large portions of 13q, that the homozygosity occurs in vivo and not as an event secondary to culture of the tumor cells, that chromosome 13 homozygosity is not correlated with the degree of histopathologic differentiation of the tumor, and that the homozygosity occurs in both sporadic and hereditary retinoblastomas. The development of chromosome 13 homozygosity may represent a fundamental event in the oncogenesis of a considerable number of retinoblastomas. This finding may have implications for the genetic counseling of patients with hereditary retinoblastoma. It may also be important in understanding the mechanism of oncogenesis of other tumors, especially hereditary tumors.

Alleles↗
PubMed1984

Looking for epilepsy genes.

The complexity of the human genome creates special problems in understanding the genetic component of disease processes. An estimated 50,000 genes exist in the human genome and it is reasonable to assume that mutation in any one of these genes may result in an inherited disorder. Because of the complex pattern of gene expression controlling the development and organization of the central nervous system, insights into the genetic component, if any, of diseases such as epilepsy are most accessible to analysis by genetic linkage studies. Advances in the manipulation of DNA have made possible more effective acquisition of genotypic information in humans by studying the inheritance of restriction fragment length polymorphisms using cloned DNA probes. Two approaches exist to utilize this technology in studying inherited disorders. The first approach consists of genotypic determinations in affected families with cloned genes in which a mutation might result in the phenotype observed. Analysis of these data will show whether the inheritance of an allele of the candidate gene is linked to the disease. The second approach relies upon the construction with these probes of a linkage map for the human genome such that disease families can be screened in order to determine with which of these markers the phenotype is linked, indicating the map position of a gene associated with the inherited disorder. The use of these new approaches enables investigators to screen either specific biochemical defects in disease families or to identify the underlying genetic mechanisms in inherited disorders whose phenotype is expressed only in the intact human.

Chromosome Mapping↗
PubMed1984

Suppression of high-grade ventricular ectopic activity by antiarrhythmic drug treatment as a marker for survival in patients with chronic coronary artery disease.

In order to investigate the relationship between the ease of suppression of complex (frequent multiform, repetitive, and early) ventricular premature beats (VPBs) and subsequent survival, 50 consecutive patients with chronic coronary artery disease (CAD) were followed retrospectively during a mean observation period of 16 months. A total of 124 drug trials were performed using single or combined class I, II, and III antiarrhythmic drugs. Thirty-nine patients were considered "responders" (elimination of Lown classes greater than or equal to IVa and reduction of greater than 30 multiform VPBs to occasional unifocal VPBs during Holter monitoring), whereas in 11 patients VPBs could not be adequately suppressed ("nonresponders"). There were no significant differences in age and congestive heart failure in the two groups. There were three deaths (one sudden) in the 39 "responders" but five deaths (three sudden) in the 11 "nonresponders" (p less than 0.01 for all deaths, p less than 0.05 for sudden deaths). Cumulative probability of survival at 12 months was 0.93 for "responders" and 0.64 for "nonresponders" (p less than 0.005). Significant side effects necessitated drug withdrawal in four patients. Our data suggest that survival in patients with CAD is better when complex VPBs can be suppressed.

Adult↗
PubMed1984

Rearing rats with mice prevents induction of mouse killing by lesions of the septum but not lesions of the medial hypothalamus or medial accumbens.

Rats which had been reared with mice and those which had not were subjected to lesions of the septum, medial accumbens, medial hypothalamus, or sham lesions. Forty-eight hours later all animals were presented with a mouse and the frequency of mouse killing recorded. In rats with lesions of the septum, the lesions induced killing only in those animals which had not been reared with mice. Rats with lesions of the medial accumbens or medial hypothalamus killed significantly more often than control animals even when they had been reared with mice. These results suggest that the septum, medial accumbens and medial hypothalamus subserve different functions in the inhibitory modulation of mouse killing behavior.

Animals↗
PubMed1984

A comparison of prey eating by spontaneous mouse killing rats and rats with lateral septal, medial accumbens, or medial hypothalamic lesions.

Rats with lesions of the medial hypothalamus and spontaneous mouse killing rats were tested for mouse and rat pup killing in their living cages 1 and 3 days postoperatively. The lesioned and spontaneous killers did not differ significantly in amount of prey eaten within 10 min following a mouse kill on either Day 1 or 3 postoperatively. Both groups ate significantly more of the prey than did sham-lesioned rats that were presented with a freshly killed mouse. When 4 hr was allowed for eating following a kill, rats with lesions of the lateral septum, medial accumbens, and medial hypothalamus each ate significantly more than spontaneous mouse killing rats. The greater prey eating by the lesioned animals is probably not the result of the prey being a highly palatable food since rats with medial hypothalamic lesions but not those with medial accumbens or septal lesions showed enhanced consumption of a sweetened lab chow over a 4 hr period. The quantitative similarity in the prey eating by spontaneous and lesion-induced mouse killers in the period immediately following the kill serves to further establish a relationship between these two kinds of killing. The greater eating that occurs in lesioned animals when a longer time is allowed for eating is consistent with other observations of excesses in the killing behavior of lesioned animals relative to spontaneous killers.

Animals↗
PubMed1984

Dissociation of prey killing and prey eating by naloxone in the rat.

Mouse killing rats matched for killing latency and prey eating were injected (IP) with 0.5, 2.0, or 5.0 mg/kg naloxone or 0.9% saline. Naloxone did not significantly inhibit prey killing or alter prey killing latency at any dose but did reduce prey eating by 50% at the two higher doses. The dissociation of prey killing and prey eating by naloxone is consistent with other evidence that these two behaviors are separate components of predation in rats.

Aggression↗
PubMed1984

Restriction sites containing CpG show a higher frequency of polymorphism in human DNA.

Unique loci in the human genome were examined with restriction enzymes in order to detect restriction fragment length polymorphisms (RFLPs). Of 31 arbitrary loci, nine were detectably polymorphic, reflecting ten polymorphic restriction sites. Nine of the ten polymorphic sites were revealed with two restriction enzymes, Msp I and Taq I, whose recognition sequences have in common the dimer sequence CpG. The cytosines in the CpG sequence are known to be frequently methylated in mammals, and the occurrence of significant variation in Msp I and Taq I sites supports the view that methylated cytosine residues are hotspots for mutation in mammalian DNA.

5-Methylcytosine↗
PubMed1984

Cytochrome P-450 in culture forms of Trypanosoma cruzi.

Trypanosoma cruzi epimastigote and trypomastigote forms contain microsomal peptides in the 40-60,000 mol. wt region, some of which are heme-staining-positive and are induced by phenobarbital, as indicated by SDS-gel electrophoresis and by double-labeling experiments. Epimastigotes show induced peptides of mol. wt 56,000, 52,000, 49,000, 44,000, 42,000 and 40,500 whereas only one peptide (52,500 mol. wt) is increased in trypomastigotes. Fractionation of microsomes derived from epimastigotes by octylamine Sepharose-4B column chromatography reveals the presence of two heme peptides with mol. wt of 55,800 and 56,600. The pooled fraction has a typical cytochrome P-450 CO-difference spectrum and appears to correspond to a high spin form. The demonstration of the existence of this family of hemoproteins in T. cruzi further supports the idea that resistance to chemotherapeutic agents is due to active metabolism. The active metabolism, however, may not be similar in the various developmental forms of this organism since differences exist in the patterns of induction of heme-positive microsomal peptides.

Animals↗
PubMed1984

DNA polymorphic loci mapped to human chromosomes 3, 5, 9, 11, 17, 18, and 22.

Using the techniques of Southern filter hybridization and somatic cell genetics, seven genomic DNA fragments recognizing DNA polymorphic loci were mapped to specific chromosomes and regions of chromosomes. The seven probes, isolated from human genomic libraries, lacked repetitive sequences and were hybridized to DNA isolated from a set of human-rodent somatic cell hybrids segregating human chromosomes. These probes detected DNA sequences on human chromosomes 3, 5, 9, 11, 17, 18, and 22. These DNA polymorphic sites, which occur in 10% or greater of the population, will serve as markers for linkage studies with known polymorphic loci as well as to establish linkage with disease loci.

Animals↗
PubMed1984

Genetic mapping of the human X chromosome by using restriction fragment length polymorphisms.

Using a human X chromosome-specific DNA library, we have found arbitrary single-copy DNA sequences that reveal useful restriction fragment length polymorphisms. The inheritance of these and other available polymorphic DNA markers has been studied in a series of unrelated three-generation families with large sibships. These families reveal parental phase and allow determination of recombination frequencies by counting recombinant and nonrecombinant chromosomes. The resulting genetic map indicates that the minimal distance from Xp22 to Xqter is 215 recombination units. The spacing of the marker loci is such that the majority of the loci on the X chromosome, including disease loci, will lie within 20 centimorgans of at least one of these loci.

Chromosome Mapping↗
PubMed1984

Adrenal pseudocyst in a hypertensive patient.

An adrenal "mass" was discovered radiologically during a hypertensive evaluation. Because of the patient's labile hypertension, the mass was interpreted as a pheochromocytoma. Only at operation was the cystic and benign nature of the lesion appreciated. Pathologically, it proved to be a simple pseudocyst.

Adrenal Gland Diseases↗
PubMed1984

Nursing: past trends, future policies.

This paper looks at five historical trends in the field of macro-policy making for nursing. From these it postulates that nursing is, now, a pluralist structure with three main interest groups. Each interest group has its own view of reality and therefore its own goals and strategies, some of which are in conflict with those of the other groups. Furthermore, the goals of the nursing groups are also in conflict with those of the government health department. The paper proposes a typology for nursing which takes account of these conflicts, helps to identify the areas of conflict and makes a proposal for the future structure which would help to achieve a more harmonious framework in the NHS.

Humans↗
PubMed1984

Altruism is not enough: barriers in the development of nursing as a profession.

This paper discusses the goals and strategies used by nurses to achieve professional status. It describes the several interest groups in nursing and identifies the plurality of their goals and the sometimes conflicting strategies used by them. The paper illustrates the constraints experienced by the Royal College of Nursing in policy making and proposes a pluralist structure as a basis for future planning.

Goals↗