Biomedical subjects

N J Martin

Publications and source records attributed to N J Martin.

35 records · Page 2Linked to original sources

PubMed1985

Duplication 5q(5q22----5q33): from an intrachromosomal insertion.

We report on an infant with an as yet undescribed partial duplication 5q(q22----5q33). He had a number of the already recorded manifestations of partial trisomy 5q, namely microcephaly, growth retardation, brachydactyly, long flat philtrum, thin upper lip vermilion and downturned angles of mouth and apparently low set ears. He survived only 6 months. He inherited his duplication from a maternal intrachromosomal insertion; thus he represents a pure dup(5)(q22----5q33).

Abnormalities, Multiple↗

PubMed1984

Effects of oligomycin and quercetin on the hydrolytic activities of the (Na+ +K+)-dependent ATPase.

Quercetin inhibited a dog kidney (Na+ + K+)-ATPase preparation without affecting Km for ATP or K0.5 for cation activators, attributable to the slowly-reversible nature of its inhibition. Dimethyl sulfoxide, a selector of E2 enzyme conformations, blocked this inhibition, while the K+-phosphatase activity was at least as sensitive to quercetin as the (Na+ + K+)-ATPase activity, all consistent with quercetin favoring E1 conformations of the enzyme. Oligomycin, a rapidly-reversible inhibitor, decreased the Km for ATP and the K0.5 for cation activators, and its inhibition was also diminished by dimethyl sulfoxide. Although oligomycin did not inhibit the K+-phosphatase activity under standard assay conditions, a reaction presumably catalyzed by E2 conformations, its effects are nevertheless accommodated by a quantitative model for that reaction depicting oligomycin as favoring E1 conformations. The model also accounts quantitatively for effects of both dimethyl sulfoxide and oligomycin on Vmax, Km for substrate, and K0.5 for K+, as well as for stimulation of phosphatase activity by both these reagents at low K+ but high Na+ concentrations.

Adenosine Triphosphatases↗

PubMed1984

Factors influencing referrals for prenatal cytogenetic diagnosis.

This paper reports the results of an investigation into factors influencing the referral of women for prenatal cytogenetic diagnosis, following mid-second-trimester amniocentesis. The overall diagnostic amniocentesis rate for women over the age of 35 years was 16.8%. One hundred and forty consecutive Brisbane women referred to the 2 Queensland laboratories offering chromosome analysis of amniotic fluid cells were included in this study. 72% were referred for advanced maternal age. The socioeconomic status (SES) of the 140 women was skewed very significantly towards the professional and semiprofessional classes (Classes A and B on the Congalton Australian Four-point Scale). Twenty seven percent of all women are in SES Class D in the Brisbane population, but only 7.4% of such women (SES Class D) were within the group studied. Forty nine percent of women indicated that they themselves raised the question of prenatal diagnosis with their doctor. Diagnostic amniocentesis is not acceptable to a certain proportion of couples, but it is estimated that 60% would accept it if there were medical indications, and if it were offered. Our studies have indicated that of those women who are at increased risk of having a child with a significant chromosomal abnormality (including those over the age of 35 years) and to whom prenatal diagnosis is acceptable, 28% are actually receiving it in current practice. Those who do are a well informed, self-motivated upper and middle class group.

Adult↗

PubMed1983

Register of chromosomal abnormalities in Queensland.

The development and use of the computer-aided retrieval of karyotypes (CAROK), a register of chromosomal abnormalities in Queensland, is described. The six independent cytogenetic laboratories serving the population of 2.2 million contribute data to the register which provides total population information on the occurrence of chromosomal abnormalities, without selection. CAROK policy on confidentiality, security, access, and safety of data is described in detail. A cytogenetic register such as this ensures a reliable permanent file of results, facilitates research, and provides a data base which will enable questions of clustering or secular trends to be answered efficiently. The register is complete for the years 1976-1981, and contains information on 880 consecutive abnormal cases; in this sense, the data constitute an unselected six-year series of diagnosed chromosomal abnormalities in Queensland. These figures show an average incidence figure (over a six-year period) for newly diagnosed cases of chromosomal abnormality of 6.61/100 000 general population per year.

Aneuploidy↗

PubMed1983

The dup(3)(p25 leads to pter) syndrome: a case with holoprosencephaly.

We report a patient with dup(3p) syndrome with holoprosencephaly. This infant is compared with 17 others reported previously with banding studies. In 72% of cases the duplication derived from a mother with a balanced translocation; 78% of affected individuals are males. The most common anomalies are characteristic facial changes, congenital heart defects, and hypoplasia of male genitalia. Holoprosencephaly has not been reported before in the dup(3p) syndrome.

Abnormalities, Multiple↗

PubMed1983

Enhancing the sensitivity of an immunoradiometric assay for thyrotropin.

Explore the source record for details and available documents.

Humans↗

PubMed1982

The ring chromosome 13 syndrome.

A study of the ring chromosome 13 syndrome is presented with detailed clinical and cytogenetic features of three new unrelated cases. The clinical limits of this syndrome can now be defined. An analysis of these cases together with those in the literature indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of knowledge. The chromosome breakpoints in the first two cases are 13p11 and 13q32 and in the third case 13p11 and 13q33 or 13q34. All described cases of the ring 13 syndrome have breakpoints within the region bounded by bands 13q21 to 13q34. All rings are negative for silver banding. Peripheral blood cultures showed an average of 88% of metaphases to be 46,XX,r(13), with the remaining 12% manifesting either random loss or ring duplication. The rings vary in size and show a variable number of centromeres. An estimate of the birth incidence of this condition in the Anglo-Saxon population is 1 in 58,000. Parents of affected children are clinically and cytogenetically normal, the rings in affected offspring being meiotic in origin.

Abnormalities, Multiple↗

PubMed1982

A ? developmental characteristic of the ultrastructure of childhood leukaemic lymphoblasts.

Areas of chromatin demarcated from the rest of the nucleus ("separations") were found frequently in acute lymphoblastic leukaemias of childhood, in some patients in apparently all leukaemic cells, but rarely in non-lymphocytic leukaemias. In normal lymphocytes, separations were most common in fetal thymus, and less frequent in fetal lymph node and bone marrow, and child thymus, lymph node and marrow. Separations may be a developmental marker, and fetal lymphoid tissues, especially thymus, may have significance in the origin of lymphoblastic leukaemias of childhood. Nuclear loops enclosing cytoplasmic material were associated with, and may have similar significance to, separations.

Bone Marrow Cells↗

PubMedDate not supplied

Assessing reproducibility of data obtained with instruments based on continuous measurements.

Data obtained with any research tool must be reproducible, a concept referred to as reliability. Three techniques are often used to evaluate reliability of tools using continuous data in aging research: intraclass correlation coefficients (ICC), Pearson correlations, and paired t tests. These are often construed as equivalent when applied to reliability. This is not correct, and may lead researchers to select instruments based on statistics that may not reflect actual reliability. The purpose of this paper is to compare the reliability estimates produced by these three techniques and determine the preferable technique. A hypothetical dataset was produced to evaluate the reliability estimates obtained with ICC, Pearson correlations, and paired t tests in three different situations. For each situation two sets of 20 observations were created to simulate an intrarater or inter-rater paradigm, based on 20 participants with two observations per participant. Situations were designed to demonstrate good agreement, systematic bias, or substantial random measurement error. In the situation demonstrating good agreement, all three techniques supported the conclusion that the data were reliable. In the situation demonstrating systematic bias, the ICC and t test suggested the data were not reliable, whereas the Pearson correlation suggested high reliability despite the systematic discrepancy. In the situation representing substantial random measurement error where low reliability was expected, the ICC and Pearson coefficient accurately illustrated this. The t test suggested the data were reliable. The ICC is the preferred technique to measure reliability. Although there are some limitations associated with the use of this technique, they can be overcome.

Aging↗

PubMedDate not supplied