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Biomedical subjects

M Sadler

Publications and source records attributed to M Sadler.

15 recordsLinked to original sources
PubMed1994

Changes in measurements of body fat distribution accompanying weight change.

The waist-to-hip circumference ratio (WHR), as an indicator of body fat distribution is related to several clinical diseases. Whether one can reduce this ratio with weight loss is still unconfirmed and may differ between sexes. The degree to which WHR changes with weight gain is also unclear. Changes in waist and hip circumferences and WHR accompanying changes in weight over 5 years were examined in 3,753 black and white men and women initially ages 18-30. Those who gained weight increased their WHR and in most cases those whose weight remained stable increased their WHR. Those who gained the most weight had the greatest increases in WHR. Men had greater increases in WHR per kg weight gain than women. In general, weight loss was accompanied by a decrease in the WHR. However, in those whose initial WHR was below the median, weight loss was associated with an increase in WHR. Smokers and black males also had increases in WHR with weight losses up to 4.9 kg.

Adipose Tissue↗
PubMed1993

Health care use by frequent marijuana smokers who do not smoke tobacco.

Even though marijuana smoke contains carcinogens and more tar than tobacco smoke and marijuana intoxication has been implicated as a risk factor for injuries, relatively little epidemiologic evidence has identified marijuana use as a risk factor for ill health. This study is the first to examine the health effects of smoking marijuana by comparing the medical experience of "daily" marijuana smokers who never smoked tobacco (n = 452) with a demographically similar group of nonsmokers of either substance (n = 450). Marijuana smoking status was determined during multiphasic health checkups at Kaiser Permanente medical centers between July 1979 and December 1985. Medical records were reviewed for as long as 2 years after the checkups. Frequent marijuana smokers had small increased risks of outpatient visits for respiratory illnesses (relative risk [RR] = 1.19; 95% confidence interval [CI] = 1.01, 1.41), injuries (RR = 1.32; CI = 1.10, 1.57), and other types of illnesses (RR = 1.09; CI = 1.02, 1.16) compared with nonsmokers; their risk of being admitted to a hospital was elevated but not statistically significant (RR = 1.51; CI = 0.93, 2.46). Analyses were adjusted for sex, age, race, education, marital status, and alcohol consumption. Daily marijuana smoking, even in the absence of tobacco, appeared to be associated with an elevated risk of health care use for various health problems.

Adult↗
PubMed1991

A study of the effect of perchloroethylene exposure on semen quality in dry cleaning workers.

The purpose of this investigation was to determine the effects of perchloroethylene (PCE) exposure on human semen quality. We compared the semen quality of 34 dry cleaners with that of 48 laundry workers. We examined the relationships of 17 semen parameters to expired air levels of PCE and to an index of exposure based on job tasks in the last three months. The average sperm concentration was over 80 million for both dry cleaners and laundry workers, but approximately one-quarter of each group was oligospermic. The overall percentage of abnormal forms was similar for the two groups; however, sperm of dry cleaners were significantly more likely to be round (t = -3.29, p = 0.002) and less likely to be narrow (t = 2.35, p = 0.02) than the sperm of laundry workers. These effects were dose-related to expired air levels and to the exposure index after controlling for potential confounders (e.g., heat exposure). The average percent motile sperm for both groups was slightly over 60%; however, sperm of dry cleaners tended to swim with greater amplitude of lateral head displacement (ALH) than those of laundry workers (t = -1.73, p = 0.09), and level of PCE in expired air was a significant predictor of ALH in the multiple regression model (t = 2.00, p = 0.05). In addition, exposure index was a significant negative predictor of the sperm linearity parameter (t = -2.57, p = 0.01). These results suggest that occupational exposures to PCE can have subtle effects on sperm quality. Additional analyses are required to determine whether these effects are associated with changes in fertility.

Adult↗
PubMed1989

Topological Link-Vertex Analysis of the growth of Purkinje cell dendritic trees in normal, reeler, and weaver mice.

The growth of Purkinje cell dendritic trees in normal, reeler, and weaver mice has been defined by using Link-Vertex Analysis. Growth probably occurs in three phases in normal and cortically located reeler trees. Phase I, completed by 7 days postnatum (dpn), establishes a rudimentary tree of 100 segments by random terminal branching. Phase II lasts from 7 to 20 dpn when some 690 and 450 segments are generated in normal and cortical reeler trees respectively. Phase II is initiated by an inductive stimulus mediated by a finite number of parallel fibres. Thereafter, dendritic trees develop a similar topology in normal and cortical reeler Purkinje cells through random interactions between parallel fibres and dendritic growth cones. We have defined this process with the aid of computer simulation techniques. Interactions appear to be restricted to a narrow growth front occupied by the highest centrifugally ordered terminals behind which adhesions occur at a greatly reduced frequency. The cortical reeler tree thus has fewer segments than normal because fewer parallel fibres are available, but it is surprisingly normal in most other respects. Phase III is a period of remodelling and extends from 20 dpn into adulthood when high-ordered terminals are eroded and middle-ordered terminals are added, with no change in total segment number in both normal and cortical reeler trees. Weaver and deeply placed reeler Purkinje cell dendritic trees are not influenced by parallel fibres. Accordingly, their growth is arrested at the end of Phase I, when both types of mutant tree have generated 100 segments by unrestrained random terminal branching. In the absence of parallel fibres, Phase II is not induced and remodelling, characteristic of Phase III, does not occur.

Aging↗
PubMed1988

Link-Vertex Analysis of Purkinje cell dendritic trees from the murine cerebellum.

A method of analysis of dendritic trees is described, called Link-Vertex Analysis, which defines the branching patterns (topology) by means of a discontinuous function, the terminal/link (T/L) vertex ratio, computed at all successive vertex orders within a network, and represented as a graphical plot for a given tree. The T/L vertex ratio is defined as the number (n) of terminal (pendant) vertices (Vp) divided by the total number (n) of all link vertices (both dichotomous, Vd, and trichotomous, Vt) multiplied by the number of segments arising from each vertex--i.e., nVp/(2nVd + 3nVt) per vertex order. Hypotheses of growth are simulated by computer modelling and the distributions of computer generated T/L vertex ratios per order compared with those of actual dendritic trees. The differential distribution of T/L vertex ratios per order in trees grown by either random terminal or random segmental branching discriminates between these two forms of growth. Significant advances of this method include the detection of regional variations in growth and remodelling in a tree and the incorporation of Vt with little perturbation of the Vd data. The analytical powers of this method have been tested using the dendritic fields of 20-day-old mouse cerebellar Purkinje cells defining possible temporal sequences and relative contributions of random and non-random terminal growth, and also the frequency of branching over a growth front relative to that of the rest of the tree.

Animals↗
PubMed1986

Three morphologically distinct types of interface develop between adult host and fetal brain transplants: implications for scar formation in the adult central nervous system.

The development of the host/graft interface of cerebellar and cerebral transplants was studied 1-60 days after operation. Grafts from fetal Wistar rats were transplanted to a cavity over the superior colliculus of adult rats by removing parts of the overlying cortex and hippocampus according to the Björklund/Stenevi technique. In sham-operated control rats, in which a cavity was made in the brain but no graft was implanted, the parenchyma bordering the entire cavity developed a complete glial-meningeal scar within 2 weeks after operation consisting of multilayered glial processes, a basal lamina, and fibroblasts (meningeal cells). A similar interface also developed between graft and host in the most superficial parts of the transplantation cavity. In the basal parts of the transplantation cavity, the host/graft interface consisted either of an incomplete sheet of astrocyte processes aligned in parallel to each other but without a covering basal lamina or of completely fused neuropil without any morphological signs of separation between host and transplant. It is concluded that these three zones of host/graft interface are established by differential interaction between the growing transplant and the host cicatrix. At the basal host/graft parenchymatous interface the fetal transplant interferes with the normal adult cicatrization process of the host, possibly by either releasing inhibitory factors or by preventing contact between the astroglia of the host and fibroblasts (meningeal cells). In white matter regions of the transplantation cavity, voluminous cysts developed, both in sham-operated controls and in graft recipients, which were invaded by transplanted neurons.

Animals↗
PubMed1986

Vertex analysis of neural tree structures containing trichotomous nodes.

Vertex analysis defines dichotomous networks in terms of the relative frequencies of pendant (Vp) and nodal (Vd) vertices. Va, Vb and Vc comprise the 3 classes of Vd which connect 2, 1 and 0 Vp respectively. The vertex ratio (VR) of Va/Vb may be used to define topology since Va and Vc approach equality in large networks. The introduction of trichotomous nodes (Vt, comprising Va', Vb', Vc' and Vd', connecting 3, 2, 1 and 0 Vp) confounds vertex analysis in as much as the values of VR must be recalculated to maintain the definition of topology. Each Vt is equivalent to 2Vd. Va', Vc' and Vd' may be unequivocally transformed into Va + Vb; Vb + Vc; and 2Vc respectively. However, Vb' potentially contains Va, Vb and Vc in proportions which must be arbitrarily set, since the mode of growth only determines the frequencies of Vt and not their transformation into Vd pairs. We have assumed that all possible pairs of transformed Vb' are equally likely and, accordingly, Vb' is equivalent to Va/3 + 4Vb/3 + Vc/3. The values of VR for different modes of growth, featuring different frequencies of Vt, may thus be obtained by computer growth simulation. The mode of growth of observed networks may thereby be ascertained from VR, providing all Vt are detectable in the tree.

Dendrites↗
PubMed1986

Destruction of meningeal cells over the newborn hamster cerebellum with 6-hydroxydopamine prevents foliation and lamination in the rostral cerebellum.

Intracisternal injection of 30 micrograms 6-hydroxydopamine was used to destroy meningeal cells in the newborn hamster. After 20 or 30 days the cerebella of treated animals showed severe morphological alterations including: an absence of distinct folia anterior to the primary fissure; a disruption of lamination in the same region by the displacement of both Purkinje cells and cerebellar interneurons; a reduction in size and frequency of branching of the medullary tree with anomalous anterobasal branches and splaying; reductions in the area of the molecular layer, the total area occupied by granule cells, the length of the pial surface and the length of the Purkinje cell layer of 29, 21, 57 and 27%, respectively; disorganization of the radially organized glial scaffold by outgrowth of Bergmann glial fibers and displacement of their cell bodies, the Golgi epithelial cells, and anomalous orientation, polarity, size and branching frequency of Purkinje cell dendritic trees. These findings support our earlier hypothesis that the initial destruction of meningeal cells destabilizes the cerebellar surface (basal lamina and glia limitans superficialis) and disorganizes the glial scaffold, while the neuronal cerebellar malformations are secondary to this glial defect.

Aging↗
PubMed1986

Primary malignant tumours of the trigeminal nerve.

We report a case of primary malignant schwannoma of the trigeminal nerve, and review the 5 previously reported cases. Clinical presentation, along with radiological and pathological features are discussed.

Combined Modality Therapy↗
PubMed1984

Remodelling during development of the Purkinje cell dendritic tree in the mouse.

The development of the Purkinje cells in normal C57 mice was studied from 7-100 d post natum . The growth of the dendritic trees was analysed both metrically and topologically using the method of vertex analysis (Berry & Flinn 1983 a). Granule and PUrkinje cell counts were made so that Purkinje cell segment production could be correlated with the number of parallel fibres deposited. Both topological and metrical results indicate that from 7 to 30 d post natum the Purkinje cell dendritic trees expand massively; accounting for 87% of total segment elaboration, reaching their lateral boundaries by 12-15 d post natum and then advancing towards the pial surface. Continued lateral expansion is constrained by the proximity of dendrites from neighbouring trees. Growth proceeds upwards through the neuropil as a front of prolific random terminal branching with inhibitory forces acting at the edges of the growth corridor and behind the growth front to prevent overlapping of dendrites. By 30 d post natum all boundaries are reached and the size of the dendritic field is fixed. Trees averaged 711.2 segments +/- 21.45 with a mean distance from root to terminal segment of 133.5 +/- 2.9 micrometers. The Va/Vb vertex ratios and the levels of trichotomy during this period indicate that branching patterns deviate from pure random terminal additions in a dichotomous tree. There is opportunity for non-random growth at the areas of inhibitory action. Beyond 30 d post natum remodelling occurs within the arbor which involves segment loss in the subpial region (orders above 16) and segment elaboration within the tree (orders 8-16) causing increased density of dendrites and overlapping of segments. The frequencies of segments and terminals are restored to symmetrical distributions through the orders of the trees from the skewed distributions associated with the frontal advance in earlier growth. During remodelling the Va/Vb vertex ratios and percentage of trichotomous nodes are consistent with growth through dichotomous random terminal branching. Path lengths of 8 micrometers between each order are seen as regular increments throughout entire trees at 100 d post natum . The final tree produced is indistinguishable from a network grown entirely by random terminal dichotomous branching with some 6% trichotomy and a Va/Vb vertex ratios of 0.92. Granule cell number within the granular layer increases rapidly up to 15 d post natum after which cell death causes a decrease to stable levels beyond 30 d post natum .(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1983

Unsuspected multiple sclerosis.

Five patients known to have various medical problems were found unexpectedly at autopsy to have typical multiple sclerosis plaques. These were most often small and in a periventricular distribution in frontal, temporal, and occipital lobes. In two cases, small plaques were found in the thalamus and brain stem. The cerebellum was not involved.

Adolescent↗
PubMed1983

Morphometric study of the development of Purkinje cell dendritic trees in the mouse using vertex analysis.

Vertices are the points in an arborescence which interconnect segments and comprise terminal or pendant vertices (Vp), nodal or branching points and the root point. Branching points may be dichotomous (Vd) or trichomtomous (Vt), etc., and are subdivided into distinct two-dimensional topological entities according to the number of terminal vertices they drain, i.e. Vds comprise primary vertices (Va), connecting two Vps; secondary vertices (Vb), connecting one Vp and one Vd or one Vt; and tertiary vertices (Vc), connecting either two Vds, two Vts or one Vt and one Vd. The four types of Vt (Va', Vb', Vc', Vd') similarly connect three, two, one and zero Vps respectively. Each Vt may be transformed into two Vds thus, Va' = Va + Vb; Vb' = Va/3 + 4Vb/3 + Vc/3; Vc' = Vb + Vc and Vd' = 2Vc. Analysis proceeds by transforming mixed trees containing varying proportions of Vds and Vts into entirely dichotomous branching structures. The topology is then defined by the Va/Vb ratio which has a unique value according to the mode of growth and the frequency of Vts. Vertices are ordered by a centrifugal technique. The frequency distribution of vertices of different order allow the changes in growth characteristics and in remodelling to be detected within particular regions of the tree. Metrical parameters are readily incorporated into the analysis since all vertices are interconnected by segments of finite length and are given the same order magnitude as the vertex they drain. The analytical capabilities of the method are exemplified by its application to the study of growth and plasticity in the dendritic trees of Purkinje cells in the mouse. Growth is defined in metrical and topological terms and sites of reorganization within the mature tree are identified.

Aging↗
PubMed1980

The intracellular Na+ and K+ composition of the moderately halophilic bacterium, Paracoccus halodenitrificans.

The intracellular concentrations of Na+ and K+ in exponentially growing Paracoccus halodenitrificans were independent of the NaCl concentration of the growth medium. The observed values were approximately 100 and 300 mM for Na+ and K+, respectively. In stationary phase cells, the ultimate values for Na+ depended on the NaCl concentration of the growth medium. With cells grown in the presence of 1 M NaCl, the value was about 500 mM; for cells grown in the presence of 3 M NaCl, the value was about 1.1 M. The K+ concentration in stationary phase cells was unaffected by the NaCl concentration in the growth medium. The final value was about 100 mM. Associated with these changes were changes in the ATP pool and decreases in the activities of the NADH oxidase system and the membrane-bound ATPase. It is proposed that the decrease in the activities of these enzymes may account for the ion flows observed in stationary phase cells.

Adenosine Triphosphatases↗
PubMedDate not supplied

Vitamin D and prostate cancer: a prediagnostic study with stored sera.

This study evaluates the risk of prostate cancer in relation to serum levels of the major vitamin D metabolites, 25-hydroxyvitamin D (25-D3) and 1,25-dihydroxyvitamin D (1,25-D). Between 1964 and 1971, more than 250,000 serum samples were collected from members of the Kaiser Permanente Medical Care Plan in Oakland and San Francisco and stored for future use. Levels of 25-D and 1,25-D were measured in samples from 90 black and 91 white men diagnosed with prostate cancer before December 31, 1987 and controls individually matched on age, race, and day of serum storage. Mean serum 1,25-D was 1.81 pg/ml lower in cases than in matched controls (P = 0.002). Risk of prostate cancer decreased with higher levels of 1,25-D especially in men with low levels of 25-D. However, mean 25-D was not significantly different in cases and controls. The association of lower 1,25-D with prostate cancer was found in men above the median age of 57 years at serum storage but not younger men and was similar in black and white men. In men > or = 57 years of age, 1,25-D was an important predictor of risk for palpable and anaplastic tumors but not for tumors incidentally discovered during surgery to treat the symptoms of benign prostatic hyperplasia or well differentiated tumors.

Adult↗