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Biomedical subjects

C Ray

Publications and source records attributed to C Ray.

At least 19 recordsLinked to original sources
PubMed2006

The role of medial prefrontal cortex in context-specific inhibition during reversal learning of a visual discrimination.

Rats with medial prefrontal cortex or sham lesions were trained on a visual discrimination task designed for the eight-arm radial maze. After reaching asymptotic performance on this task, both groups were divided into sub-groups that would experience reversal learning in the same or different context from original training. The results showed that both groups reversed in the different context had accelerated learning compared to the groups reversed in the same context. Reversal learning in rats with medial prefrontal cortex damage was faster than sham animals in the same context. These and other results from a transfer test suggest that the medial prefrontal cortex participates in the behavioral effects of a context-specific inhibitory association acquired during visual discrimination learning.

Animals↗
PubMed2005

Reduction of hematotoxicity and augmentation of antitumor efficacy of cyclophosphamide by dopamine.

Modulatory effects of dopamine (DA) on hematotoxicity and antitumor efficacy of cyclophosphamide (CY) were studied in Swiss mice bearing transplantable Ehrlich ascites carcinoma (EAC). DA was administered i.p. at a dose of 50 mg/kg/day for 5 consecutive days beginning day 3 after tumor transplantation. CY (200 mg/kg i.p.) was injected 24 hour after completion of DA treatment. DA pretreatment reduced the suppressive effects of CY on hemoglobin, RBC, total WBC, neutrophil, platelet, and bone marrow nucleated cell counts. Likewise, DA partially prevented the CY-induced fall in pluripotent (CFU-S12) and lineage-specific stem cells for granulocytes (CFU-C) in bone marrow. Moreover, mice receiving a combination of DA and CY illustrated greater reduction in tumor volume, viable tumor cell count and mitotic index along with upregulation of tumor cell apoptosis than CY-only group. As a result, the former group demonstrated prolonged hosts survival. Thus, DA protected to a great extent the hematopoietic cells of tumor bearing hosts from the suppressive action of CY and concomitantly augmented its antitumor efficacy resulting in improved hosts survival.

Animals↗
PubMed2004

Microwave endometrial ablation for menorrhagia: outcome at 2 years--experience of a district general hospital.

One hundred and twenty-three women underwent microwave endometrial ablation (MEA) for the treatment of dysfunctional uterine bleeding (DUB). The mean age at treatment was 40.2 years and the average treatment time was 2 minutes 50 seconds. All patients stayed as day cases, except for two who stayed overnight, one due to pain and the other due to urinary retention. The follow-up was carried out at 6 months, 1 and 2 years, respectively. The success rate was 80%, 76% and 70% at 6 months and 1-year and 2-year follow-up. The patient satisfaction rate was 80%, 75% and 68% at 6 months, 1 year and 2 years, respectively. However, in women 45 years old and over the success rate was more than 90%, suggesting that MEA could be a preferred procedure for treatment of DUB in this age group compared to younger women, especially in those who do not benefit from the mirena intrauterine system or decline it. Approximately 70% of patients, who underwent hysterectomy due to the failure of treatment, had uterine/pelvic pathology in the form of adenomyosis, fibroid uterus or endometriosis; therefore prior to MEA, proper patient selection is vital. There were a few minor complications but no uterine perforation or emergency hysterectomies in the group studied.

Adult↗
PubMed2003

Metal-insulator transitions in an expanding metallic fluid: particle formation kinetics.

Core-level photoemission spectroscopy provides a local probe of expansion dynamics and associated transient chemical properties as a highly pressurized, metallic fluid expands into vacuum following impulsive heating of a semiconductor by an intense, ultrashort laser pulse. Transient photoemission peak shifts reveal that metal-insulator transitions occur rapidly following laser heating. These experiments probe constituents species and solidification kinetics occurring in the early moments of material ejection and provide insight into how particles arise in the current laser ablation regime.

Journal Article↗
PubMed2003

Measurement of vacuum-assisted photoionization at 1 GeV for Au and Ag targets.

We report a measurement of photon impact ionization of K and L shell of Au and K shell of Ag targets in the 1-GeV energy range. We show that the cross section is dominated by a contribution from a new channel called vacuum-assisted photoionization. In this process the energy-momentum balance associated with the removal of the innershell electron is obtained by conversion of a high-energy photon into an electron-positron pair. This measurement is consistent with the theoretical prediction that vacuum-assisted photoionization is the most probable ionization mechanism at very high energies.

Journal Article↗
PubMed2001

Decrease in platelet serotonin level in uterine cervix cancer patients.

Platelet serotonin (5-HT) concentration was measured by HPLC with electrochemical detection in 46 women suffering from cancer of the uterine cervix and 16 matched controls. About 53% reduction (p < 0.05) was recorded in platelet 5-HT level in cancer patients against a control value of 1.29 +/- 0.16 (mean +/- S.E.) nmol per 10(9) platelets. Depletion of intraplatelet 5-HT was positively correlated with clinical stage of the disease although a modest rise (p > 0.05) in platelet 5-HT was observed in patients at stage I. Serotonin release from platelets following activation with thrombin was considerably increased in cancer patients (38.2% compared to 17.4% in controls). The results demonstrate progressive depletion of intraplatelet 5-HT in cervical cancer patients. In addition, their platelets release more 5-HT than the controls upon activation by thrombin.

Biomarkers, Tumor↗
PubMed2000

The devastating potential of blunt vertebral arterial injuries.

OBJECTIVE: To formulate management guidelines for blunt vertebral arterial injury (BVI). SUMMARY BACKGROUND DATA: Compared with carotid arterial injuries, BVIs have been considered innocuous. Although screening for BVI has been advocated, particularly in patients with cervical spine injuries, the appropriate therapy of lesions is controversial. METHODS: In 1996 an aggressive arteriographic screening protocol for blunt cerebrovascular injuries was initiated. A prospective database of all screened patients has been maintained. Analysis of injury mechanisms and patterns, BVI grades, treatment, and outcomes was performed. RESULTS: Thirty-eight patients (0.53% of blunt trauma admissions) were diagnosed with 47 BVIs during a 3.5-year period. Motor vehicle crash was the most common mechanism, and associated injuries were common. Cervical spine injuries were present in 71% of patients, but there was no predilection for cervical vertebral level or fracture pattern. The incidence of posterior circulation stroke was 24%, and the BVI-attributable death rate was 8%. Stroke incidence and neurologic outcome were independent of BVI injury grade. In patients treated with systemic heparin, fewer overall had a poor neurologic outcome, and fewer had a poor outcome after stroke. Trends associated with heparin therapy included fewer injuries progressing to a higher injury grade, fewer patients in whom stroke developed, and fewer patients deteriorating neurologically from diagnosis to discharge. CONCLUSIONS: Blunt vertebral arterial injuries are more common than previously reported. Screening patients based on injury mechanisms and patterns will diagnose asymptomatic injuries, allowing the institution of therapy before stroke. Systemic anticoagulation appears to be effective therapy: it is associated with improved neurologic outcome in patients with and without stroke, and it appears to prevent progression to a higher injury grade, stroke, and deterioration in neurologic status.

Adult↗
PubMed1999

Injections given in healthcare settings as a major source of acute hepatitis B in Moldova.

BACKGROUND: Reported rates of acute hepatitis B are high in many former Soviet Union republics and modes of transmission are not well defined. METHODS: Two case-control studies were undertaken in Moldova to identify risk factors for acute hepatitis B in people aged 2-15 years (children) and > or =15 years (adults). Serologically confirmed acute hepatitis B cases occurring between 1 January 1994 and 30 August 30 1995, were matched on age, sex, and district of residence to three potential controls who were tested for hepatitis B markers to exclude the immune. Stratified odds ratios (SOR) were calculated using bivariate and multivariate methods. RESULTS: In multivariate analysis, compared with the 175 controls, the 70 adult cases (mean age 25 years, 66% male) were more likely to report receiving injections in the 6 months before illness during a dental visit (SOR = 21; 95% CI: 3.7-120), a hospital visit (SOR = 35; 95% CI: 7.2-170), or a visit to the polyclinic (SOR = 13; 95% CI: 2.4-74). Among children, receiving injections during a hospital visit (SOR = 5.2; 95% CI: 1.2-23) was the only exposure reported significantly more often by the 19 cases (mean age 8 years, 68% male) compared with the 81 controls. CONCLUSION: These results, along with reported unsafe injection practices in Moldova, suggest that injections are a major source of hepatitis B virus transmission and highlight the importance of proper infection-control procedures in preventing transmission of blood-borne infections.

Acute Disease↗
PubMed1998

Effect of diuretics on sodium and chloride permeability in the rat papillary collecting duct.

While in vivo data suggests that diuretics such as furosemide and hydrochlorothiazide alter inner medulla collecting duct (IMCD) cell electrolyte transport, this has not been confirmed by in vivo studies nor have the mechanisms been evaluated. This study evaluated the direct effect of these diuretics as well as amiloride on sodium and chloride unidirectional permeability in the isolated perfused rat IMCD. In the absence of diuretics, the permeability of sodium was lower than that of chloride (0.63 +/- 0.05 compared with 0.83 +/- 0.08 micrometer/s), although both were relatively impermeable when compared to water. Furosemide (10(-4)) and hydrochlorothiazide (10(-3)) both increased the diffusional permeability of chloride by approximately 30% (0.80 +/- 0.06 to 1.04 +/- 0.09 micrometer/s, p < 0.01, and 0.74 +/- 0.09 to 0.98 +/- 0.10 micrometer/s, p < 0.02, respectively). However, sodium permeability was unaltered. Inhibition of Na+, K+-ATPase by ouabain or cooling (4 degrees C) inhibited basal sodium but not chloride permeability while a maximal antidiuretic AVP concentration did not alter sodium or chloride permeability. However, increasing the lumen and bath sodium chloride concentration from 150 to 300 and 600 mM significantly increased both sodium and particularly chloride conductance. In contrast, amiloride (10(-4)) significantly reduced both sodium and chloride permeability. These studies support a direct effect of furosemide and hydrochlorothiazide on the IMCD and suggest that their in vivo effect is primarily mediated by facilitating the passive movement of chloride into the lumen via a favourable electrochemical gradient. These results also demonstrate that amiloride inhibits both sodium and chloride unidirectional permeability by mechanisms separate to that of the sulphonamide-related diuretics.

Amiloride↗
PubMed1997

Lateral approach for endoscopic removal of solitary osteochondromas from the distal radial metaphysis in three horses.

A lateral approach to the carpal sheath was used for endoscopic removal of osteochondromas from the distal aspect of the radius in 3 horses. Previously osteochondromas have been removed through an incision into the carpal sheath; however, endoscopy is less invasive, requires less surgery and convalescence time, provides better cosmetic results, is associated with a lower risk of infection, and allows better examination of structures within the sheath. A medial approach for endoscopic removal has been described previously; however, the lateral approach was advantageous, because it avoided the median vein, artery, and nerve and because the sheath was more easily distended from the lateral approach. Therefore, this approach may be an alternative for removal of osteochondromas from the distal aspect of the radius in horses.

Animals↗
PubMed1997

Mechanisms of alcohol impairment of recovery from mechanically denuded areas made within cultured rat hepatocytes.

The effect of ethanol on the ability of a denuded hepatocyte cell surface to recover is unknown. We therefore determined the effect of ethanol on the rate of renewal of mechanical wounds made in near-confluent monolayers of primary cultures of rat hepatocytes. We found that ethanol exerted a dose-dependent effect to impair rat hepatocyte recovery and that at least 12 hours of exposure to ethanol was required to induce this impairment. The effect of ethanol to impair recovery of denuded areas of epithelium was not seen in two established renal tubular epithelial cell lines. Ethanol impairment of rat hepatocyte recovery could be blocked by an alcohol dehydrogenase inhibitor (4-methyl pyrazole) and potentiated by an inhibitor of aldehyde dehydrogenase (pargyline). The effect of ethanol to inhibit rat hepatocyte recovery of denuded areas was not associated with any change in hepatocyte cell surface expression of the beta1 integrin subunit as determined by flow cytometry. These results suggest that acetaldehyde is responsible for ethanol inhibition of hepatocyte recovery from mechanical injury and that this impairment occurs independent of cell surface expression of the beta1 integrin subunit.

Animals↗
PubMed1997

Coping and other predictors of outcome in chronic fatigue syndrome: a 1-year follow-up.

In this prospective study, 137 patients with chronic fatigue syndrome were followed-up at a 1-year interval to determine factors relating to outcomes. Nearly two thirds reported an improvement on direct ratings of change. In analyses with fatigue and functional impairment at follow-up as the criteria, and controlling for earlier status, poorer outcomes were predicted by illness duration, subjective cognitive difficulty, and somatic symptoms; there was no influence of anxiety, depression, or general emotional distress. Fatigue was also predicted by information-seeking, and impairment by behavioral disengagement and a low internal locus of control. The belief that one's actions can influence outcomes modified the relationship between illness accommodation and both fatigue and impairment; adverse outcomes were associated with accommodating to illness only in the context of lower levels of perceived control. Thus, it is suggested that interventions that either discourage avoidance of activity or enhance perceived control could benefit the course of the illness.

Adaptation, Psychological↗