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Biomedical subjects

C M Young

Publications and source records attributed to C M Young.

At least 19 recordsLinked to original sources
PubMed2001

Deep-sea ecology. Developmental arrest in vent worm embryos.

Temperature is a key factor in controlling the distribution of marine organisms and is particularly important at hydrothermal vents, where steep thermal gradients are present over a scale of centimetres. The thermophilic worm Alvinella pompejana, which is found at the vents of the East Pacific Rise (2,500-m depth), has an unusually broad thermotolerance (20-80 degrees C) as an adult, but we show here that the temperature range required by the developing embryo is very different from that tolerated by adults. Our results indicate that early embryos may disperse through cold abyssal water in a state of developmental arrest, completing their development only when they encounter water that is warm enough for their growth and survival.

Animals↗
PubMed2001

Larval dispersal potential of the tubeworm Riftia pachyptila at deep-sea hydrothermal vents.

Hydrothermal vents are ephemeral because of frequent volcanic and tectonic activities associated with crust formation. Although the larvae of hydrothermal vent fauna can rapidly colonize new vent sites separated by tens to hundreds of kilometres, the mechanisms by which these larvae disperse and recruit are not understood. Here we integrate physiological, developmental and hydrodynamic data to estimate the dispersal potential of larvae of the giant tubeworm Riftia pachyptila. At in situ temperatures and pressures (2 degrees C and 250 atm), we estimate that the metabolic lifespan for a larva of R. pachyptila averages 38 days. In the measured flow regime at a fast-spreading ridge axis (9 degrees 50' N; East Pacific Rise), this lifespan results in potential along-ridge dispersal distances that rarely exceed 100 km. This limited dispersal results not from the physiological performance of the embryos and larvae, but instead from transport limitations imposed by periodic reversals in along-ridge flows and sustained episodes of across-ridge flow. The lifespan presented for these larvae can now be used to predict dispersal under current regimes at other hydrothermal vent sites.

Animals↗
PubMed2001

Olanzapine therapy in treatment-resistant psychotic mood disorders: a long-term follow-up study.

BACKGROUND: Recent studies suggest a role for the atypical antipsychotic olanzapine in the acute treatment of psychotic mood disorders, but long-term data are unavailable. The purpose of this naturalistic study was to determine the long-term effectiveness and tolerability of olanzapine as add-on therapy in psychotic mood disorders. METHOD: Hospital records were reviewed for 125 inpatients at the state psychiatric hospital in Buffalo, N.Y., who received at least 6 weeks of add-on olanzapine treatment for psychotic mood disorders (schizoaffective disorders [bipolar and depressive type], bipolar disorders [I, II, and NOS], and major depressive disorder). A group of schizophrenic patients served as a control group (N = 50). Baseline measures, including age, gender, number of hospitalizations in the 2 years prior to olanzapine treatment, concomitant medications, the Clinical Global Impressions scale (CGI), and the Global Assessment of Functioning-Equivalent (GAF-EQ) and Kennedy Axis V psychological impairment, violence, social skills, and activities of daily living subscale scores, were obtained. Follow-up information was obtained from the patients at least 6 months after initiation of olanzapine or by chart review and discussion with the treating psychiatrist. Patients with a diagnosis of psychotic mood disorders were compared with patients with the non-affective psychotic disorder (schizophrenia) on a variety of outcome measures. RESULTS: Follow-up information was available on 102 patients (82%). Mean follow-up was 15 months; 50 (49%) of the 102 patients remained on olanzapine treatment at follow-up (32 psychotic mood disorder, 18 schizophrenic). The primary reason for discontinuation in both groups was lack of response. Both the psychotic mood disorder and schizophrenic groups had comparable outcomes on the CGI and GAF-EQ. Improvement on the Kennedy Axis V psychological impairment and social skills subscales was seen only in the psychotic mood disorders group (p < .01); both groups showed significant (p < .02) improvement in the violence subscale. Sustained mood-stabilizing effect was evident in only 7/27 (26%) of the psychotic mood disorders patients continuing on add-on olanzapine treatment at follow-up. CONCLUSION: Lack of response was the primary reason for discontinuation of add-on olanzapine in both groups. Mood symptoms predicted a better response to add-on olanzapine in patients with psychotic mood disorders on selective outcome measures. However, only 26% of the patients with psychotic mood disorders sustained a clinically meaningful mood-stabilizing effect with add-on olanzapine treatment at follow-up.

Adult↗
PubMed2000

Epidermal lesions and mortality caused by vibriosis in deep-sea Bahamian echinoids: a laboratory study.

When significant mortality of the bathyal spatangoid echinoid Paleopneustes cristatus occurred under laboratory conditions, we investigated the cause and course of the disease by culturing and identifying internal pathogens, then experimentally infecting healthy urchins with isolates of the suspected disease organism. The pathogen was determined to be the gram-negative halophilic bacterium Vibrio alginolyticus. This species was also recovered from frozen post-challenge specimens of P. cristatus and from moribund individuals of Archaeopneustes hystrix, another spatangoid reared under similar in vitro conditions. This is the first experimental study of bacterial disease in any deep-sea invertebrate.

Animals↗
PubMed2000

Methane ice worms: Hesiocaeca methanicola colonizing fossil fuel reserves.

During a research cruise in July 1997 in the Gulf of Mexico we discovered a gas hydrate approximately 1 m thick and over 2 m in diameter which had recently breached the sea floor at a depth of 540 m. The hydrate surface visible from the submarine was considerably greater than that of any other reported hydrate. Two distinct color bands of hydrate were present in the same mound, and the entire exposed surface of the hydrate was infested (2500 individuals/m2) with 2 to 4 cm-long worms, since described as a new species, Hesiocaeca methanicola, in the polychaete family Hesionidae (Desbruyères and Toulmond 1998). H. methanicola tissue stable isotope values are consistent with a chemo-autotrophic food source. No evidence of chemo-autotrophic symbionts was detected, but geochemical data support the presence of abundant free living bacteria on the hydrate. The activities of the polychaetes, grazing on the hydrate bacteria and supplying oxygen to their habitats, appears to contribute to the dissolution of hydrates in surface sediments.

Animals↗
PubMed2000

New and emerging therapies for vitiligo.

Vitiligo is a common skin disease; however, it still remains a difficult disease to treat. Not all patients respond to current forms of treatment. There are several new treatments, surgical and nonsurgical, and immunologic, that appear to either have higher success rates than past therapies or have potential as future developments for therapy of vitiligo.

Adjuvants, Immunologic↗
PubMed2000

The sagittal band: anatomic and biomechanical study.

Forty-eight digits from 12 human adult fresh-frozen and formalin-preserved cadaveric hands were used to study the anatomy and biomechanics of the sagittal band (SB) and to investigate the mechanism of its injury. The SB was observed to be part of a complex retinacular system in proximity to the metacarpophalangeal (MCP) joint collateral ligaments and the palmar plate. Dynamic changes in SB fiber orientation were observed with different positions of the MCP and wrist joints. The fibers were perpendicular (0 degrees ) to the extensor tendon in neutral position, distally angulated 25 degrees at 45 degrees of MCP flexion, and 55 degrees with full flexion. Swan-Ganz catheter measurements were obtained deep to the SB in varying positions of the MCP joint. The average pressure generation was greatest (50 mm Hg) during full MCP joint flexion and least (30 mm Hg) during 45 degrees flexion. When MCP joint radial or ulnar deviation was added the average measurement was greatest (57) in neutral MCP position and least (35 mm Hg) in 45 degrees flexion. Serial sectioning of the ulnar SB produced no extensor tendon instability. Partial proximal but not distal sectioning of the radial SB produced tendon subluxation. Complete sectioning of the radial SB produced tendon dislocation. Wrist flexion increased tendon instability after radial SB sectioning. We conclude that (1) extensor tendon instability following SB disruption is most common in the long finger and least common in the small finger; (2) ulnar instability of the extensor tendon is due to partial or complete radial SB disruption, (3) the degree of extensor tendon instability is determined by the extent of SB disruption, (4) proximal rather than distal SB compromise contributes to extensor tendon instability, (5) great forces are inflicted on the SB while the MCP joint is in full extension or less frequently in full flexion, which may be the mechanism of its injury, and (6) wrist flexion contributes to extensor tendon instability after SB disruption and may exacerbate the severity of its injury.

Adult↗
PubMed2000

Larval development of the tropical deep-sea echinoid Aspidodiadema jacobyi: phylogenetic implications.

The complete larval development of an echinoid in the family Aspidodiadematidae is described for the first time from in vitro cultures of Aspidodiadema jacobyi, a bathyal species from the Bahamian Slope. Over a period of 5 months, embryos grew from small (98-micron) eggs to very large (3071-micron) and complex planktotrophic echinopluteus larvae. The fully developed larva has five pairs of red-pigmented arms (preoral, anterolateral, postoral, posterodorsal, and posterolateral); fenestrated triangular plates at the bases of fenestrated postoral and posterodorsal arms; a complex dorsal arch; posterodorsal vibratile lobes; a ring of cilia around the region of the preoral and anterolateral arms; and a long, unpaired posterior process containing a fenestrated rod. The presence of a posterior process and posterodorsal arms makes the larva of Aspidodiadema jacobyi much more similar to larvae of irregular urchins in the order Spatangoidea than to other families of the order Diadematoida, to which the family is normally assigned. This unexpected larval form lends support to a recommendation that the Aspidodiadematidae should be either elevated to ordinal status as a sister group of the order Diadematoida, or split off as a sister group of the other families within the order. In either case, if we accept the parsimonious hypothesis that the aboral process and posterodorsal arms were derived only once in the evolutionary history of euechinoids, then the larval data suggest that the Aspidodiadematidae may be very near the node where the irregular and regular euechinoids first diverged.

Animals↗
PubMed1996

Duplex assessment of venous reflux and chronic venous insufficiency: the significance of deep venous reflux.

PURPOSE: This study was undertaken to examine the role of superficial and deep venous reflux, as defined by duplex-derived valve closure times (VCTs), in the pathogenesis of chronic venous insufficiency. METHODS: Between January 1992 and November 1995, 320 patients and 500 legs were evaluated with clinical examinations and duplex scans for potential venous reflux. VCTs were obtained with the cuff deflation technique with the patient in the upright position. Imaging was performed at the saphenofemoral junction, the middle segment of the greater saphenous vein, the lesser saphenous vein, the superficial femoral vein, the profunda femoris vein, and the popliteal vein. Not all patients had all segments examined because tests early in the series did not examine the profunda femoris or lesser saphenous vein and because some patients had previous ligation and stripping or venous thrombosis. VCTs were examined for individual segment reflux, grouped into superficial and deep systems, and then correlated with the clinical stage as defined by the SVS/ISCVS original reporting standards in venous disease. Segment reflux was considered present if the VCT was greater than 0.5 seconds, and system reflux was considered present if the sum of the segments was greater than 1.5 seconds. Between-group differences were analyzed with analysis of variance and post hoc tests where appropriate. RESULTS: Sixty-nine limbs studied were in class 0, 149 limbs were in class 1, 168 limbs were in class 2, and 114 limbs were in class 3. VCTs in the superficial veins were significantly lower in class 0 than in the other clinical classes. There was no difference in superficial reflux in the symptomatic limbs (classes 1 to 3). Reflux VCTs in the superficial femoral and popliteal veins increased as the clinical symptoms progressed, with a significant increase in class 3 ulcerated limbs when compared with nonuclerated limbs. The incidence of deep venous reflux was 60% in class 3 limbs, compared with 29% in class 2 limbs, whereas the incidence of superficial venous reflux did not differ among the symptomatic limbs. Isolated superficial femoral and popliteal vein reflux was uncommon, even in class 3 limbs, but combined superficial femoral and popliteal vein reflux was found in 53% of class 3 limbs, compared with 18.5% of class 2 limbs. CONCLUSIONS: Reflux in the deep venous system plays a significant role in the progression of chronic venous insufficiency. Deep system reflux increases as clinical changes become more severe, with significant axial reflux contributing to ulcer formation.

Analysis of Variance↗
PubMed1991

Young adults' knowledge of the strength of different alcoholic beverages.

Providing information about the strength of different alcoholic beverages is a common component of alcohol abuse prevention programs. However, little is known about drinkers' knowledge of the strength of different alcoholic beverages. In the present study, 113 young adult drinkers responded to a questionnaire concerning the alcohol content of different types of malt beverages (beers, malt liquors), wines, fortified wines (port, sherry), and distilled spirits. The results indicated rates of correct responses well below 50 percent for each type of alcoholic beverage, with a substantial proportion of subjects either overestimating or underestimating alcohol content. Not a single subject reported correct alcohol content values for all four beverage types. There was a trend towards less accurate estimates of the alcohol content of strength were less accurate than those of men. The results are discussed in terms of prevention of alcohol abuse.

Adult↗
PubMed1990

The Michigan Alcoholism Screening Test: false positives in a college student sample.

The Michigan Alcoholism Screening Test (MAST), designed and validated by Selzer (1971), is widely used to screen for persons with alcohol problems. The most recent version of the MAST includes the question "Have you ever attended a meeting of Alcoholics Anonymous (AA)?" This question may contribute to false positive identifications, as it does not specify whether attendance is for the subject's own problem drinking. In the current research, 114 college students completed the MAST along with an additional question: "Have you ever attended a meeting of Alcoholics Anonymous because of your own problem drinking?" The results indicated that seven of 114 subjects (6.1%) attained inflated MAST scores because they had attended an Alcoholics Anonymous meeting, but not for their own problem drinking. It is suggested that the wording to the Alcoholics Anonymous question on the MAST be changed to reduce the number of false positive identifications produced by this instrument.

Adult↗
PubMed1990

The relative biological effectiveness of fractionated doses of fast neutrons (42 MeVd----Be) for normal tissues in the pig. II. Late effects on cutaneous and subcutaneous tissues.

The late effects of irradiation with single and fractionated doses of X rays (250 kV) and fast neutrons (42 MeVd----Bc), on the cutaneous and subcutaneous tissues of the pig, have been evaluated from measurements of changes in relative field length. These were determined at intervals of 26-104 weeks after irradiation. For fractionated irradiation with X rays the average fractions exponent, N, obtained from a log-log plot of iso-effect dose (ED50) against fraction number was 0.41. This was independent of the period of assessment, with no significant indication of a time factor. However, the exponent N did vary with the level of effect and was in the range 0.33-0.51. It was greatest for a greater than or equal to 10% reduction in relative field length. Assuming the validity of the linear quadratic model of cell survival, the alpha/beta ratio was 1.95 Gy. However, this model fitted the data less well for the least severe levels of damage, and for these the alpha/beta ratios were not significantly different from zero. Irradiation with fast neutrons showed a small effect of fractionation for doses given in greater than or equal to 6 fractions compared with a single dose. There was no significant increase in iso-effect dose when the dose was given in 30 fractions compared with 6 fractions. The relative biological effectiveness for late cutaneous and subcutaneous damage for the energy of fast neutrons used did not vary with the period of assessment, i.e. 26-52 weeks compared with 65-104 weeks, and was not significantly different from that previously obtained for ischaemic dermal necrosis, seen after higher doses, at 12-20 weeks after irradiation.

Animals↗
PubMed1989

Depletion of hypothalamic norepinephrine reduces the fever induced by polyriboinosinic acid: polyribocytidylic acid (Poly I:Poly C) in rats.

Administration of either Poly I:Poly C (0.05-0.50 micrograms) or norepinephrine (2-8 micrograms) into the anterior hypothalamic area produced a dose-related fever in rats. The fever induced by Poly I:Poly C was attenuated after selective depletion of norepinephrine in the hypothalamus. However, selective depletion of hypothalamic norepinephrine did not affect the fever induced by intrahypothalamic norepinephrine. The data indicate that Poly I:Poly C may act to induce fever through the endogenous release of norepinephrine from the rat's hypothalamus.

Animals↗
PubMed1989

Ischaemia reperfusion injury in pedicle skin flaps in the pig: lack of protective effect of SOD and allopurinol.

A model of ischaemia and reperfusion was established which consistently achieved a 50% reduction in viable length of random pattern pedicle skin flaps in pigs. Flaps were subjected to two periods of ischaemia and reperfusion. Superoxide dismutase (SOD) in a dose of 3000 mu/kg given intravenously and allopurinol 70 mg/kg/day orally had no effect on viable skin flap length, skin blood flow or histological characteristics of flaps. SOD polymers, which have been used in other species to delay SOD clearance, were found to cause anaphylactoid reactions in pigs.

Allopurinol↗