Search PubMed⌕ Search

Biomedical subjects

M Cook

Publications and source records attributed to M Cook.

At least 55 records · Page 3Linked to original sources
PubMed1989

Lead absorption in indoor firing range users.

To determine if users of indoor firing ranges may be at risk from lead exposure, we studied a law enforcement trainee class during three months of firearms instruction. Blood lead levels were obtained before training and at four-week intervals during training. Air lead levels were measured three times during instruction. Blood lead levels rose from a pre-training mean of 0.31 mumol/L to 2.47 mumol/L. Mean air lead levels were above 2,000 micrograms/m3, more than 40 times the Occupational Safety and Health Administration's standard of 50 micrograms/m3. Cumulative exposure to lead and the change in blood lead were positively correlated. Control measures need to be studied to determine their efficacy in decreasing or eliminating this health risk.

Air Pollutants↗
PubMed1988

Possible case of hyperparathyroidism in a Roman period skeleton from the Dakhleh Oasis, Egypt, diagnosed using bone histomorphometry.

A histomorphometric study of thin femoral head sections of a skeletal sample from the Dakhleh Oasis, Egypt, dated from circa 36 B.C. to 400 A.D., identified an adult female (Dk31-A1) in her mid-50s with a high percentage resorption surface with tunneling resorption as is typically found in hyperparathyroidism. Five static histomorphometric bone parameters were measured with the following results for this individual: 1) mean wall thickness, 41.94 micron, 2) trabecular bone volume, 18.54%, 3) surface volume, 4,070 mm2/cm3, 4) mean trabecular diameter, 132 microns, and 5) total resorption surface, 12.31%. The overall histomorphometric features and differential diagnosis support the diagnosis of hyperparathyroidism. We conclude that histomorphometry of dried bone, particularly in this case where preservation is ideal, is a valuable investigative technique for paleopathology.

Bone and Bones↗
PubMed1987

Role of genetic variation at the fibrinogen locus in determination of plasma fibrinogen concentrations.

Three restriction fragment length polymorphisms (RFLPs) of the fibrinogen genes were used in 91 individuals to investigate the role of genetic variation at this locus in the determination of plasma fibrinogen. The strongest association was with a polymorphism detected with the beta-fibrinogen probe and the enzyme BclI. The probe detects two alleles, designated B1 and B2. The individuals with the genotype B1B1 had a mean fibrinogen of 2.74 g/l; those with B2B2 had a mean fibrinogen of 3.69 g/l (a level previously associated with a strongly increased risk of ischaemic heart disease); and those heterozygous for the two alleles, with the genotype B1B2, had a mean of 2.98 g/l. Genetic variation at the fibrinogen gene locus accounted for 15% of the total phenotypic variance in fibrinogen.

Female↗
PubMed1987

Lead exposure in a firing range.

We report lead exposure in four employees of a privately owned shooting range, one of whom had neurological toxicity due to lead. Increasing time worked at the range was associated with elevation of blood lead. This incident emphasizes the risk of airborne lead exposure to employees of firing ranges.

Air Pollutants, Occupational↗
PubMed1987

Traumatic rupture of the thoracic aorta. A review of 49 cases.

We examined retrospectively the chest radiograph of forty nine patients with angiographically proven aortic ruptures. The plain film findings found most consistently were a wide mediastinum (69.5%), partial obliteration of the descending aorta (67.3%), left apical cap (65.3%), downward displacement of the left main bronchus (65.3%), tracheal deviation to the right (63.2%), obscuration of the aortic arch (55.1%), right paratracheal stripe thickening (53%) and nasogastric tube deviation to the right (50%). We also examined 113 sequential aortograms performed after thoracic trauma over 3 years, to determine the positive rate in our series; 14 studies were positive for a rate of 12.4%. No single case of proved ruptured aorta with a normal chest radiograph was detected.

Aorta, Thoracic↗
PubMed1986

There are two gene sequences for human apolipoprotein CI (apo CI) on chromosome 19, one of which is 4 kb from the gene for apo E.

A cDNA probe corresponding to the mRNA sequence for apolipoprotein E (apo E) was used to screen two independently-constructed human genomic libraries. Two recombinants (lambda E-2, and lambda E2-1), isolated using the apo E cDNA probe, also contain part or all of the apo CI gene. Hybridisation studies using both apo E and apo CI cDNA probes show that these two genes are in the same orientation and separated by 4 kb.

Apolipoprotein C-I↗
PubMed1986

Attribute processing in patients with graphical copying disability.

This study investigated whether defective copying of multiple-line figures in lesion patients is associated with a deficit in perceptually processing and copying elementary attributes. Lesion and Control patients were assessed on a copying test comprising multi-line figures, and on parallel perceptual and motor forms of single-attribute tasks for Size, Orientation, Angle, Position and Direction. Copying test performance was correlated with perceptual attribute performance for the Lesion but not the Control group. Mean attribute performance of the Lesion patients who showed a copying disability (defined as a copying performance below the minimum performance of the Control group) was inferior to that of the non-disabled and Control subjects. The non-disabled patients did not differ from the Controls on any of these tasks. Performance in the copying test for left- and right-hemisphere patients did not differ, but left-hemisphere patients showed less impairment in the simple attribute tasks. The results are discussed in terms of the role of elementary perceptual deficits in copying disability and hemispheric differences in the nature of this condition.

Adolescent↗
PubMed1986

Purification, characterization, and structural properties of a single protein from rat basophilic leukemia (RBL-1) cells possessing 5-lipoxygenase and leukotriene A4 synthetase activities.

Arachidonate 5-lipoxygenase of rat basophilic leukemia (RBL-1) cells was purified more than 1000-fold by gel filtration and anion exchange protein-high performance liquid chromatography (HPLC). Physical properties of the purified 5-lipoxygenase such as molecular weight (74,000-76,000), N-terminal sequence (30 amino acids), and amino acid composition were determined. The purified enzyme converted [14C]arachidonic acid at 20 degrees to [14C] 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and to [14C]dihydroxyeicosatetraenoic acids (diHETEs). Utilizing [14C] 5(S)HPETE as substrate, the purified enzyme also converted the hydroperoxy acid to [14C]diHETES. The [14C]diHETE reaction products were identified primarily (greater than 80% of recovered radioactivity) as the nonenzymatic hydrolysis products of leukotriene A4 (i.e., 6-trans-leukotriene B4 and 12-epi-6-trans-leukotriene B4) by reverse phase HPLC, scanning spectrophotometry, and gas chromatography-mass spectrometry. The bioconversion of [14C] arachidonate and [14C]5(S)HPETE to reaction products by the purified enzyme was dependent on the presence of both Ca2+ and ATP. The enzymatic activities were inhibited in a similar manner by the lipoxygenase inhibitors nordihydroguaiaretic acid, diphenyldisulfide, and SK&F 86002. The data provide evidence that RBL-1 cell 5-lipoxygenase and leukotriene A4 synthetase activities reside on a single monomeric protein with a free N-terminus and that they possess similar biochemical characteristics.

Amino Acids↗
PubMed1985

Ultrasound in the diagnosis of jaundice--a review.

A retrospective study of 92 jaundiced patients undergoing ultrasound examination was undertaken to assess the clinical utility of this test. The patients were graded according to the likelihood of biliary obstruction. In those in whom biliary obstruction was proven to be present, the sensitivity of ultrasound to detect the obstruction was 91% and the test specificity was 100%. In patients who had undergone cholecystectomy no increase in the diameter of the common duct was observed. Liver function tests proved to be unreliable in discriminating between extrahepatic obstructive jaundice and other forms of jaundice. Ultrasound scanning is a useful screening test in the diagnosis of the jaundiced patient. However, follow-up is suggested for those with a negative result of this test but in whom biliary obstruction is suspected. An approach to the investigation of the jaundiced patient should include early ultrasound examination in those with possible biliary obstruction.

Adolescent↗
PubMed1985

The binding of leukotriene C4 and leukotriene D4 to membranes of a smooth muscle cell line (BC3H1) and evidence that leukotriene induced contraction in these cells is mediated by thromboxane, protein and RNA syntheses.

Leukotriene C4 (LTC4) and leukotriene D4 (LTD4) are important mediators of anaphylaxis and induced thromboxane (TxA2) synthesis in vivo and in vitro. The mechanism by which this occurs is not known and the cellular source of leukotriene (LT) induced TxA2 has not been identified. To obtain insights into this problem we have established an in vitro system using the BC3H1 murine smooth muscle cell line. A membrane fraction obtained from these cells contained binding sites for [3H]LTC4 having high specificity and affinity. Binding of [3H]LTC4 was saturable, specific and reversible with a dissociation constant (KD) of 33 +/- 16 nM and a maximum number of binding sites (Bmax) of 25 +/- 6 pmol/mg membrane protein. However, the amount of [3H]LTD4 specifically bound was considerably less than that of [3H]LTC4. LTC4 and LTD4 induced these cells to contract, a process which was blocked by inhibitors of cyclooxygenase and thromboxane synthetase. Using a radioimmunoassay, we have shown that the level of TxB2 (a stable metabolite of TxA2) was increased in response to LTC4 and LTD4 treatment in a dose-dependent manner. Cycloheximide, a protein synthesis inhibitor, and actinomycin D, an inhibitor of RNA synthesis, were found to inhibit both LTC4- and LTD4-induced TxB2 synthesis and cellular contraction. Arachidonic acid, in the absence of LT, increased the levels of TxB2 synthesis and contraction even in the presence of cycloheximide and actinomycin D. These data are consistent with the hypothesis that the rate-limiting step in LT-induced TxB2 synthesis is the formation of free arachidonic acid, a process which requires RNA and protein synthesis.

Animals↗
PubMed1984

Leukotriene C4 ([3H]-LTC4) binding to membranes isolated from a hamster smooth muscle cell line (DDT1MF2).

Leukotriene C4 (LTC4) has been demonstrated to induce contraction of the smooth muscle cell line DDT1MF2. A partially purified membrane fraction obtained from these cells exhibited a high affinity binding site for LTC4. Binding of [3H]-LTC4 was saturable, specific and reversible with a dissociation constant (Kd) of 21 +/- 4 nM. The maximum number of binding sites (Bmax) was 55 +/- 5 pmol/mg of protein. Specificity was demonstrated in competition studies in which the Ki of LTC4 against specifically bound [3H]-LTC4 was 12 nM whereas Leukotriene D4 (LTD4) and Leukotriene E4 (LTE4) had a Ki of 38 +/- 4 and 4.7 +/- 0.5 nM respectively. A previously described antagonist of leukotriene-induced smooth muscle contraction PFL 55712 had a Ki of 23 +/- 2 nM as determined by competition binding experiments.

Animals↗