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Biomedical subjects

A MacKenzie

Publications and source records attributed to A MacKenzie.

65 records · Page 4Linked to original sources
PubMed1991

Hox-7 expression during murine craniofacial development.

We have used in situ hybridisation to establish the temporal and spatial expression patterns of the mouse homeobox-containing gene; Hox-7, in the developing embryonic cranium and nervous system of the mouse between embryonic days 9.5 (E9.5) and E15.5. Hox-7 has previously been associated with areas of mesenchymal-epithelial interaction and cell migration especially in neural crest ectomesenchymal cells. Aside from the expression patterns seen in the facial anlage at E9.5, Hox-7 transcripts were also detected in the neuroepithelium including cells of the dorsal midline of the neural tube. This expression pattern persisted throughout the embryonic time span studied. At E11.5, expression of Hox-7 became obvious in the neuroepithelium of the forming tela choroida and the telencephelii in areas destined to form the choroid plexus before any atrophy of the neuroepithelium took place. High expression of Hox-7 was also present in the mesenchyme cells invading the pouch formed by the involuting choroid plexus neuroepithelium. A second major site where Hox-7 was expressed was the anlage of the anterior pituitary; the Rathke's pouch. Expression became obvious at E10.5 throughout the pouch but by E12.5 became more regionalised in areas of the pouch destined to form the pars distalis. Hox-7 was also expressed in the forming meninges and skull bone precursors from E10.5 onwards. Expression of the Hox-7 gene is also seen in the external ear, the forming eye, the nasal pits and forming Jacobson's organs. When these expression patterns are considered together with characterised human and mouse retinoic acid embryopathies and the congenital malformations seen in human children associated with deletion of chromosome 4p16.1 (Wolf-Hirschhorn syndrome), Hox-7 may be a good candidate as one of the genes involved in the initiation of the choroid plexus phenotype and its subsequent formation, the formation of the outer ear, formation of the dentition and the differentiation of the cell types of the anterior pituitary. The expression pattern of Hox-7 in the dorsal midline of the neural tube further suggests that it may also be involved in the specification of the dorsal-ventral axis of the developing nervous system.

Animals↗
PubMed1989

Myotonic dystrophy is closely linked to the gene for muscle-type creatine kinase (CKMM).

We have studied genetic linkage between the gene for creatine kinase muscle type (CKMM) and the gene for myotonic dystrophy (DM). In a panel of 65 myotonic dystrophy families from Canada and the Netherlands, a maximum lod score (Zmax) of 22.8 at a recombination frequency (theta) of 0.03 was obtained. Tight linkage was also demonstrated for CKMM and the gene for apolipoprotein C2 (ApoC2). This establishes CKMM as a useful marker for myotonic dystrophy.

Apolipoprotein C-II↗
PubMed1987

Marginated pool of neutrophils in rabbit lungs.

The size and location of the marginated pool of neutrophils (PMNs) in rabbit lungs were evaluated, and the rate of exchange of the PMNs with the circulating pool was determined. 99mTc-labeled erythrocytes (99mTc-RBCs) and 125I-labeled macroaggregated albumin (125I-MAA) were used to determine RBC transit times in the pulmonary circulation. Radiolabeled PMNs were studied on their first passage through the lungs. After 10 min of circulation, the lungs were fixed, gamma counted, and prepared for morphometric and autoradiographic studies; 74 +/- 3% of the PMNs was retained in the lungs on the first passage, and 23 +/- 2% was within the pulmonary marginated pool 10 min later. The regional PMN retention and the rate of exchange between the marginated and circulating PMN pools in the lung were directly related to RBC transit time. The radiolabeled PMNs distributed similarly to the unlabeled cells within the microvasculature and had a similar exchange rate between the marginated and circulating pools (1.4 +/- 0.2%/s using labeled cells and 1.5 +/- 0.5%/s using unlabeled cells). The marginated pool was located primarily within alveolar capillaries and contained two to three times as many PMNs as the total circulating pool.

Animals↗
PubMed1985

A re-assessment of the tricellular region of epithelial cell tight junctions in trachea of guinea pig.

The tricellular region of epithelial tight junctions was previously dismissed as a possible avenue of permeability. One reason was that the two parallel vertical fibers, which penetrate the depth of the tight junction, were apparently cross-linked. Another reason was that the tricellular region of the tight junction is deeper than the adjacent bicellular regions. In the course of several freeze-fracture studies of epithelial tight junctions we have made observations which led us to re-assess the tricellular region as an avenue of permeability. We believe that information from ectoplasmic fracture faces is less subject to artifacts and, in ectoplasmic fracture faces of tricellular regions, cross-linking of the vertical furrows has not been observed. In guinea pig tracheal epithelium the tricellular junction is only about 1 micron deep. Following exposure to cigarette smoke, lanthanum ion staining has been observed in some tricellular junctions. It seems that earlier reasons for dismissing tricellular regions of the tight junction as permeability sites may be insufficient and that there is some evidence to support a role in permeability.

Animals↗
PubMed1984

The structure of tight junctions in the tracheal epithelium may not correlate with permeability.

To test the hypothesis that cigarette smoke produces changes in the morphology of tight junctions guinea pigs were exposed to cigarette smoke or air in a previously standardized fashion (Simani et al. 1974). Permeability is greatest one half hour following exposure to cigarette smoke (Hulbert et al. 1981). The animals were sacrificed at that time. The tracheal epithelium was studied using both thin-section and freeze-fracture techniques. A quantitative analysis of the organization and integrity of junctional complexes was performed for each animal. Organization was assessed by measuring and comparing areas delimited by PF fibers and EF furrows. PF fiber integrity was assessed by measuring uninterrupted lengths of fibers and furrows from freeze-fracture replicas. This assessment did not demonstrate a change in tight-junction morphology following exposure to cigarette smoke.

Animals↗
PubMed1977

Use of Buf-Puf and mild cleansing bar in acne.

As a result of this clinical study with the Buf cleansing system, I believe that it offers several advantages:(1) it is effective with minimal daily use; and (2) patients report that their skin feels smoother and they are easily able to control the irritative potential by experimentally titrating their own levels of application. Based on this sampling of acne patient, I conclude that the buf cleansing system is a useful addition to the treatment modalities now available for acne.

Acne Vulgaris↗
PubMedDate not supplied

The effects of single and repeated episodes of thiamin deficiency on memory in alcohol-consuming rats.

The underlying pathogenesis of Korsakoff's syndrome, an amnesic disorder most commonly found in alcoholics, is not well understood. Chronic alcoholism is associated with thiamin deficiency and current thinking is that this may be the causal factor. In Experiment 1, rats were given a 20% (v/v) ethanol/water mix as their only source of fluid for 156 days. Three groups were made thiamin deficient through the combination of a thiamin-deficient diet and the centrally acting thiamin antagonist pyrithiamin hydrobromide, after 4, 15, and 26 weeks exposure to ethanol, respectively. The control group was given ad lib access to laboratory chow and water throughout this period. There were no differences between groups on either the working or reference versions of the Morris water tank paradigm. In Experiment 2, to test the hypothesis that a single bout of thiamin deficiency, with or without concurrent alcohol intake, is not sufficient to cause severe memory impairments, two groups of rats were subjected to three bouts of thiamin deficiency. One of these groups consumed an ethanol/water mix, the other tap water. A third group was made thiamin deficient on only one occasion. The control group was not made thiamin deficient and consumed lab chow and tap water throughout. Once again, there were no between-group differences in the data derived from testing in either the eight-arm radial maze or the Morris water tank task. These experiments indicate that the aetiology of Korsakoff's syndrome is more complex than previously thought.

Alcohol Drinking↗
PubMedDate not supplied

Case management in the Community Psychiatric Nursing Service in Hong Kong: describing the process.

PURPOSE: To explore the roles, functions, and work practices of case managers and their perceptions on the implementation of case management in the Community Psychiatric Nursing Services. METHODS: A qualitative descriptive approach was used. Data were collected from daily reports, field observations, reflective diaries, and small group interviews. FINDINGS: The study showed the work practices of case managers were more intensive compared to the conventional community psychiatric nursing practice, and there was more involvement of clients and their family in the treatment process. Case managers identified liaison, coordination, supportive and family counseling, and teaching practical living skills as their important roles. CONCLUSIONS: This study provides valuable information in understanding the process of case management and contributed to the development of case management as a care delivery model in Hong Kong.

Case Management↗