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Biomedical subjects

J D Hicks

Publications and source records attributed to J D Hicks.

At least 19 recordsLinked to original sources
PubMed2004

Concurrent changes in serum vitamin B12 and methylmalonic acid during cobalt or vitamin B12 supplementation of lambs while suckling and after weaning on properties in the South Island of New Zealand considered to be cobalt-deficient.

AIM: To compare serum analyses of vitamin B12 and methylmalonic acid (MMA) as indices of cobalt/vitamin B12 deficiency in lambs around weaning. METHODS: Lambs on five properties, considered to be cobalt- deficient, were supplemented with either cobalt bullets, or short- or long-acting vitamin B12 preparations. Blood samples, and in some cases liver biopsies, and liveweights were obtained at monthly intervals. Serum samples were assayed for vitamin B12 and MMA and liver for vitamin B12 concentrations. Pasture cobalt concentrations were measured on three of the properties. RESULTS: Pasture cobalt concentrations were generally maintained below 0.07 microg/g dry matter (DM) on the properties sampled. Growth responses to supplementation were observed on only 2/5 properties, despite serum vitamin B12 concentrations being within the currently used 'marginal' reference range (336-499 pmol/L) for at least 3 months on all properties and in the deficient reference range (0-335 pmol/L) for at least 2 months on all farms except one. Serum MMA concentrations in supplemented lambs were <2 micromol/L, except in those animals sampled 1 month after receiving treatment with a short-acting vitamin B12 injection. Serum MMA concentrations in unsupplemented animals on properties on which no growth response to supplementation occurred generally reached peak levels of between 4 and 7 micromol/L at the nadir of serum vitamin B12 concentration. When a growth response was observed, differences in weight gain between supplemented and unsupplemented lambs occurred as mean serum MMA concentrations increased from 9 to 14 micromol/L. On one property where supplementation commenced before weaning, normal growth rates were maintained despite serum vitamin B12 concentrations of 140 pmol/L and serum MMA concentrations in excess of 40 micromol/L serum. CONCLUSIONS: The possibility that current serum vitamin B12 references ranges for diagnosis of cobalt deficiency are set too high and lead to over-diagnosis of responsiveness to cobalt/ vitamin B12 supplementation is discussed. The suggestion is made that serum MMA concentrations in excess of 9-14 micromol/L will provide a more reliable diagnostic test for cobalt deficiency. However, there was sufficient variation between properties in the relationships between cobalt concentrations of pasture and serum vitamin B12 or MMA concentrations to require more rigorous testing of the reliability of using serum MMA concentration for this purpose. The possibility that differences in rumen fermentation and therefore propionate and vitamin B12 production could be involved is discussed. The measurement of serum MMA and vitamin B12 appears to be of little value whilst the lamb is still suckling. CLINICAL SIGNIFICANCE: Serum MMA concentration may offer advantages over serum vitamin B12 concentrations in the diagnosis of a cobalt/vitamin B12 responsiveness in weaned lambs.

Journal Article↗
PubMed2001

Tissue contributions to sex and race: differences in tooth crown size of deciduous molars.

This study describes size of constituent deciduous tooth crown components (enamel, dentine, and pulp) to address the manner in which males characteristically have larger teeth than females, and the observation that teeth of American blacks are larger than those of American whites. Measurements were collected (n = 333 individuals) from bitewing radiographs using computer-aided image analysis. Tissue thicknesses (enamel, dentine, pulp) were measured at the crown's mesial and distal heights of contour. Deciduous mesiodistal molar crown length is composed of about 1/7 enamel, 1/3 dentine, and 1/2 pulp. Details differ by tooth type, but males typically have significantly larger dentine and pulp dimensions than females; there is no sexual dimorphism in marginal enamel thickness. Males scale isometrically with females for all variables tested here. Blacks significantly exceed whites in size of all tissues, but tissue types scale isometrically with blacks and whites with one exception: enamel thickness is disproportionately thick in blacks. While the absolute difference is small (5.56 mm of enamel in blacks summed over all four deciduous molar tooth types vs. 5.04 mm in whites), the statistical difference is considerable (P < 0.001). Aside from enamel, crown size in blacks is increased proportionately vis-à-vis whites. Principal components analysis confirmed these univariate relationships and emphasizes the statistical independence of crown component thicknesses, which is in keeping with the sequential growth and separate embryonic origins of the tissues contributing to a tooth crown. Results direct attention to the rates of enamel and dentine deposition (of which little is known), since the literature suggests that blacks (with larger crowns and thicker enamel) spend less time in tooth formation than whites.

Anthropology, Physical↗
PubMed1998

A radiographic assessment of enamel thickness in human maxillary incisors.

Crown sizes of human teeth are sexually dimorphic, with male larger than female. This holds for most human groups, though the extent of dimorphism varies among populations. It is not known whether size dimorphism is due to differences in enamel thickness, dentine differences, or some combination of the two. This study examined the pattern of variation in enamel thickness on the mesial and distal margins of the four maxillary permanent incisors. Standardized periapical radiographs of the incisors of 115 adolescent American whites were measured. Enamel was significantly thicker on the distal than the mesial margins of both the lateral and central incisors, with a mean difference of 0.1 mm. There was no sexual dimorphism in the maximum mesial or distal enamel thicknesses. In contrast, the widths of the dentine of the crowns were significantly greater in males, by an average of 6.5%. Sexual dimorphism in mesiodistal diameters of the incisors seems, then, to be due to the dentine component, which is the size attained at the end of the bell stage of tooth formation. Sex-specific correlations between enamel thickness and crown width of the dentine were low (and lower for males), indicating considerable independence between regulatory mechanisms of dentine and enamel development.

Adolescent↗
PubMed1996

Motivating workers.

Explore the source record for details and available documents.

Housekeeping, Hospital↗
PubMed1994

Evaluation of health, sanitation, and nutrition in Forces Command Child Development Centers.

In 1992, Forces Command had 42 Child Development Centers on 22 installations. We evaluated program compliance in the areas of health, sanitation, and nutrition using inspection findings from April 1991 through June 1992. Each program was rated on 20 items, using inspection checklists developed for this evaluation. We also surveyed Haemophilus influenza type b (Hib) vaccination records among enrolled children. Most programs and facilities were fully or partially compliant in most areas. By quantifying the inspection findings, we were able to identify compliance items that needed further attention. The most frequent problem area across all programs was documentation of child immunization and health records. For children between 13 and 60 months of age, 77.7% had records indicating appropriate vaccination against Hib. Comparisons with the prior year's findings indicated a trend toward improvement.

Child↗
PubMed1983

Primary lymphoma of the heart. A case report.

The necropsy findings of a large cell lymphoma involving only the pericardium and myocardium in a 62-year-old woman are reported. The initial presenting symptoms were heart failure followed by rapidly progressive heart block. The diagnosis of cardiac lymphoma was suggested by gallium and blood pool isotope studies, and was subsequently confirmed by operative myocardial biopsy. The clinical course was abrupt, and the patient died before therapy was instituted. While primary cardiac lymphoma is an extremely rare condition, experience in this case suggests that noninvasive isotope studies, particularly gallium and blood pool, are helpful in the diagnosis of atypical cardiomyopathy.

Diphosphates↗
PubMed1981

Ocular complications in high-dose chemoradiotherapy and marrow transplantation.

Patients who have received marrow transplants and total body irradiation with different forms of chemotherapy should be routinely watched by an ophthalmology service because of the high incidence of dry eye syndrome, viral keratitis, and trophic disturbances of the cornea. Herpes simplex keratitis must be strongly suspected in bizarre corneal findings associated with geographic epithelial denudement accompanying acute GVHD. Acute GVH ocular syndrome warrants clinical recognition when, in the course of severe GVHD, the eyes reveal keratoconjunctivitis with associated herpes simplex infections of the cornea, later to show chronic problems of severe drying conjunctival and corneal scarring compatible with Stevens-Johnson syndrome.

Adolescent↗
PubMed1979

IgG1 hypergammaglobulinaemia in chronic parasitic infections in mice: magnitude of the response in mice infected with various parasites.

Mice chronically infected with 3 metazoan and 1 protozoan parasite contain in their circulation levels of IgG1 which are increased over the levels in uninfected mice by at least 10x. In the case of infection with the larval cestode, Mesocestoides corti, the serum IgG1 concentration can reach greater than 50 mg/ml and, with a half-life of less than 2 days, the number of cells engaged in IgG1 production is approximately 2 x 10(8). The IgG1 hypergammaglobulinaemia is not seen in infected hypothymic nude mice. Biosynthetic labelling studies with organ and tissue cultures established that in two of the chronic infections the organs principally involved in IgG1 synthesis were those pathologically involved or those "in line" for antigen capture: i.e. liver and spleen in the case of M. corti which is located in the liver and the peritoneal cavity, and various intestinal lymph nodes in the case of the gut-dwelling nematode, Nematospiroides dubius. This apparently exaggerated response to chronic parasitic infection is of interest simply because of the potential magnitude of the effect and the fact that it involves an Ig isotype with very poorly defined biological function.

Animals↗
PubMed1978

Lymph node and splenic imprints: their value in diagnosis.

Comparison was made of the value of information obtained from imprints and from histological sections of lymph nodes from 100 biopsies on patients with mainly haematological disorders and 55 spleens removed surgically. The sections provided the definitive diagnosis. It was seldom possible to make a definite diagnosis from imprints, but they provide additional information useful in interpreting the histology of sections.

Hematologic Diseases↗
PubMed1975

Histiocytic medullary reticulosis.

The clinical and pathological features of histiocytic medullary reticulosis (HMR) are described in five patients. Treatment by splenectomy and the MOPP routine resulted in a transient improvement in platelet and neutrophil counts and resolution of anaemia and apparent prolongation of survival in two of the five patients. The relationship of HMR to other histiocytic disorders is discussed. HMR is defined as a unique malignant histiocytosis in which malignant histiocytes engage in phagocytosis of eryrhrocytes, leucocytes and platelets.

Adult↗