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J D McLean

Publications and source records attributed to J D McLean.

18 recordsLinked to original sources
PubMed1984

High-resolution electron microscopy of octacalcium phosphate and its hydrolysis products.

The hydrolysis and dehydration products of synthetic octacalcium phosphate (OCP) were studied using X-ray diffraction, infrared spectroscopy, chemical analysis, and high-resolution electron microscopy (HREM). A "collapsed OCP" phase, identified by a characteristic 16.5 A reflection in its X-ray diffraction pattern, was observed when OCP was dehydrated. High resolution electron microscopy of the hydrolyzed and partially hydrolyzed reaction products also revealed local contrast features with an approximate 16.5 A periodicity. These features were consistent with a collapse of the OCP crystal structure and subsequent formation of epitaxial intergrowths of OCP and hydroxyapatite. Chemical analysis and X-ray diffraction of these samples were similar to previously reported calcium-deficient apatites. The hydrolysis of OCP to form calcium-deficient apatites is a reaction pathway which may be of importance in understanding the crystallographic changes occurring during the early stages of bone, calculus, and dental enamel formation.

Apatites↗
PubMed1983

A high-resolution electron microscope study of synthetic and biological carbonated apatites.

A series of synthetic carbonated apatites and human dental enamels characterized by chemical analysis, infrared spectroscopy, and X-ray diffraction was studied using high-resolution transmission electron microscopy. Steps on the surfaces of apatite crystals, often only a few unit cells high and occasionally one unit cell high, were observed by their Fresnel diffraction contrast. Highly substituted synthetic carbonated apatites appeared to have more irregular and finer-textured surface features than materials with less carbonate substitution. The surface features of enamel apatite crystal were also irregular, but surface steps were less frequently aligned in crystallographic directions. Complex strain fields due to radiation damage centers were observed in some crystals and the fine structure of dislocations and grain boundaries in synthetic apatites was resolved at high magnification. Experimental lattice-image contrasts, in favorable circumstances, could be matched to computer-simulated images and were found to contain detail at near atomic resolution, around 2.0-2.5 A.

Adult↗
PubMed1983

Negative impact of computerized record keeping in a psychiatric department.

A general hospital psychiatric inpatient department which had been regarded as efficient and effective in its functioning, underwent rapid deterioration after the introduction of a computerized system of charting and record keeping. The deterioration was attributed to: 1) Impeded communication among the staff; 2) Loss of time available for patient care; 3) Staff frustration with the system and subsequent feelings of anger and helplessness being communicated to the patients. The authors describe the development of this deterioration and discuss possible psychodynamic factors and suggested corrective-preventative measures.

Communication↗
PubMed1983

Unusual side effects of clomipramine associated with yawning.

Although there have been previous reports of decreased sexual capacity as a side effect of antidepressants (1-3), the authors know of no previous records of increased capacity of the type described in the following reports, or of reports of side effects associated with yawning. Observation of unusual yawning-associated side effects is now reported, in order to alert clinicians to a possible side effect that can influence patient-compliance with the prescribed medication regimen.

Adult↗
PubMed1978

Hyperlipaemia in ponies.

The case histories and clinical findings of 15 ponies with hyperlipaemia are presented. The disease was characterised by hyperlipidaemia with inappetance, progressing somnolence, muscle fasciculation, diarrhoea, and ventral oedema as the predominant clinical findings. Post mortem examinations of 12 ponies showed extensive lipidosis and vascular thrombosis with widespread secondary changes. Most cases occurred in late pregnant and early lactating mares in the summer months and it is postulated that the disease was initiated in this group by a falling nutritional plane in the face of high nutrient requirements.

Animals↗
PubMed1970

A general method for the specific staining of intracellular antigens with ferritin-antibody conjugates.

A general method is described whereby an intracellular macromolecule can be specifically stained with its antibody conjugated to ferritin. In this method cells or cell organelles are fixed, embedded in bovine serum albumin cross-linked with glutaraldehyde or formaldehyde, and then sectioned. This procedure preserves antigenic determinants as well as the cellular ultrastructure. The application of the ferritin-antibody conjugate to the section produces specific staining of the exposed antigen.

Animals↗
PubMedDate not supplied

Benzene and total hydrocarbon exposures in the upstream petroleum oil and gas industry.

Occupational exposures to benzene and total hydrocarbons (THC) in the Canadian upstream petroleum industry are described in this article. A total of 1547 air samples taken by 5 oil companies in various sectors (i.e., conventional oil/gas, conventional gas, heavy oil processing, drilling and pipelines) were evaluated and summarized. The data includes personal long- and short-term samples and area long-term samples. The percentage of samples over the occupational exposure limit (OEL) of 3.2 mg/m3 or one part per million for benzene, for personal long-term samples ranges from 0 to 0.7% in the different sectors, and area long-term samples range from 0 to 13%. For short-term personal samples, the exceedance for benzene is at 5% with respect to the OEL of 16 mg/m3 or five parts per million in the conventional gas sector and none in the remaining sectors. THC levels were not available for all sectors and had limited data points in others. The percentage exceedance of the OEL of 280 mg/m3 or 100 parts per million for THC as gasoline ranged from 0 to 2.6% for personal long-term samples. It is recommended that certain operations such as glycol dehydrators be carefully monitored and that a task-based monitoring program be included along with the traditional long- and short-term personal exposure sampling.

Benzene↗