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Biomedical subjects

N Garcia

Publications and source records attributed to N Garcia.

At least 55 records · Page 3Linked to original sources
PubMed2000

Intermittent vs continuous hypoxia: effects on ventilation and erythropoiesis in humans.

OBJECTIVE: Recently, we showed that 5 days of normobaric intermittent hypoxia at rest (IH; 2 hours daily at 3,800 m simulated altitude; partial pressure of inspired oxygen 90 torr) can induce an increase in the isocapnic hypoxic ventilatory response (HVR) and blood reticulocyte count. The purpose of the present study was to compare these data with continuous exposure to the same hypoxic level. METHODS: Four of the same subjects were exposed, a year later, to 2 days of continuous hypoxia (CH), and 4 different subjects were exposed to 8 weeks of CH, both at the White Mountain Research Station (3,800 m altitude, barometric pressure approximately 489 torr). Inspired minute ventilation (VI), end-tidal partial pressure of carbon dioxide, arterial oxygen saturation (SaO2[sat]), hematocrit, and hemoglobin concentration were measured at different times during the continuous exposures. The HVR was expressed as the increase in V1 per 1% decrease in SaO2. RESULTS: The HVR showed no significant difference in the control values 1 year apart (IH, 0.06 +/- 0.03; CH2d (2 days' continuous hypoxia), 0.19 +/- 0.07 L x min(-1) x %sat(-1); means +/- SE), and the HVR values were similar after 2 days of IH compared to CH (0.42 +/- 0.26 and 0.51 +/- 0.22 L x min(-1) x %sat(-1), respectively). On the new subjects after 2 weeks of CH, the HVR showed a maximum increase, similar to the increase observed after only 5 days of IH, hemoglobin concentrations and hematocrit were significantly increased (45.0 +/- 2.7% vs 51.5 +/- 3.0% and 14.5 +/- 0.7 vs 17.2 +/- 1.0 g x dL(-1), respectively). The HVR did not change significantly from week 2 to 8 of CH, whereas hematological data were still increasing at the end of the 8 weeks. CONCLUSION: Changes in ventilatory oxygen sensitivity induced by IH and CH are similar in magnitude but occur with different time courses. The effects of IH on erythropoiesis are significant but fewer than on CH.

Acclimatization↗
PubMed1998

Pre-adaptation, adaptation and de-adaptation to high altitude in humans: hormonal and biochemical changes at sea level.

High altitude residence is known to modify body biochemistry and hormone status. However, the effects of such a sojourn on these status observed at sea level both immediately and later after return are not as well established as are the effects of an intermittent acclimation. The aim of this study was therefore to investigate these changes. To achieve our objectives, nine subjects received intermittent acclimation at low pressure in a barometric chamber (8 h daily for 5 days, day 1 at 4500 m, day 5 at 8500 m) before an expedition to the Himalayas. Hormonal and biochemical changes were studied using samples of venous blood taken at sea level before and after acclimation, after return from the expedition and 1 and 2 months after descent. Concentrations of thyroid hormones, adrenaline, noradrenaline (NA), hormones of hydromineral metabolism (aldosterone, renin, arginine vasopressin, atrial natriuretic peptide) as well as prolactin, cortisol, insulin and endothelin 1 were measured. Biochemical measurements made were plasma osmolality, and concentrations of glucose, total cholesterol, total proteins, pre-albumin, transferrin, complement 3C, apolipoproteins A1 and B and serum iron. Acclimation induced no alteration in hormone (except for NA with increases of about 1.5, fold P < 0.05) and biochemistry data. After the expedition, hormone responses were characterized by a higher total triidothyronine concentration (+18%, P < 0.05) while other hormones did not vary. A linear relationship was found between thyroid-stimulating-hormone and body mass changes after the expedition (r = 0.67, P < 0.05). The observed increased concentrations of plasma proteins and total cholesterol (P < 0.05) could be related to the restoration of lean body mass. At 1 and 2 months after return, no changes in hormones were observed but a significant decrease in transferrin concentration was noticed. The higher serum iron concentration reported after 1 month (P < 0.05) could have been the result of a physiological haemolysis. It was concluded that both acclimation and the expedition in the Himalayas affected hormone status and body biochemistry status even though the observed changes were slight and rapidly reversed.

Adaptation, Physiological↗
PubMed1998

Quality of life in breast cancer. Part II: Psychological and spiritual well-being.

With an increasing number of women surviving breast cancer beyond treatment, the focus of care has shifted from the acute treatment-related side effects to long-term effects associated with changes in quality of life (QOL). Part I of this article described the impact of breast cancer on the domains of physical and social well-being of 21 long-term survivors of breast cancer through qualitative analysis. Part II explores the impact of breast cancer on the domains of psychological and spiritual well-being.

Adaptation, Psychological↗
PubMed1997

Quality of life in breast cancer survivors as identified by focus groups.

Currently, over 1,700,000 women are living with breast cancer in the United States. These long-term survivors of breast cancer are challenged to redirect their energy from issues of cancer treatment and early side effects toward quality of life issues related to long-term survivorship, such as menopause, infertility, fear of recurrence, family distress, and uncertainty. In an attempt to obtain patient perspectives on quality of life and health care issues faced by breast cancer survivors, focus group methodology was utilized in the first year of a 2 year study. The sample was stratified to represent three age groups: < 40 years, 40-60 years, and > 60, and was intended to represent different developmental levels believed to have varying experiences with quality of life and potentially divergent needs following breast cancer diagnosis. Results of these focus groups revealed unique quality of life concerns of breast cancer survivors across four domains of physical, psychological, social, and spiritual well being. Each of these domains yields important implications for future research and clinical practice.

Adaptation, Psychological↗
PubMed1997

General and local cold responses in humans after 2 weeks at high altitude.

To investigate the effects of a short-term high altitude residence (2 weeks between 4150 m and 6885 m in the Andes) on the general and local cold responses after descent, 11 subjects were submitted both to a whole body standard cold air test (SCAT, dry bulb temperature = 1 degree C, 2 h, nude, at rest) and to a local cold water test of the right upper limb (CWT, 5 degrees C, 5 min) both before and after the expedition. Compared to before the expedition, a lower systolic blood pressure was observed after the high altitude residence [130.00 (SEM 3.35) mm Hg vs 140.40 (SEM 4.74) mm Hg at the end of CWT, P < 0.05] whereas no significant change either in diastolic blood pressure or in heart rate was found. All skin temperatures of the right upper limb were lowered (P < 0.05). During SCAT, body temperatures were unchanged (rectal and mean skin temperature, Tsk) but metabolic heat production was slightly but significantly diminished [110 (SEM 4) W.m-2 vs 125 (SEM 3) W.m-2, P < 0.05] and heat debt increased [11.37 (SEM 1.11) kJ.kg-1 vs 9.30 (SEM 2.30) kJ.kg-1, P < 0.05]. Moreover, the time of onset of continuous shivering (d) was shortened [8.20 (SEM 1.90) min vs 17.30 (SEM 3.60) min, P < 0.05] and the level of Tsk observed at (d) was higher [25.70 (SEM 0.80) degrees C vs 23.57 (SEM 0.78) degrees C, P < 0.05] suggesting an increase in the sensitivity of the thermoregulatory system despite the slight decreased shivering activity observed. It was concluded that general and local cold tolerance were modified by a short-term residence at altitude and that the changes observed were not in accordance with general or (and) local cold adaptation. In contrast, high altitude sojourn could be a risk factor for frostbite of the extremities.

Altitude↗
PubMed1997

Viremia after one month of interferon therapy predicts treatment outcome in patients with chronic hepatitis C.

BACKGROUND & AIMS: In chronic hepatitis C, interferon alfa induces sustained remission in less than 30% of treated patients. The aim of this study is to analyze viral status early after initiation interferon therapy as a predictor of treatment outcome. METHODS: One hundred eighty-one patients with chronic hepatitis C who had been treated with interferon alfa for 12 months (median follow-up, 49 months) were studied. Viremia and aminotransferase levels at the first and third months of therapy as well as 10 pretreatment variables were assessed as potential independent predictors of sustained response to treatment. RESULTS: Sustained response occurred in 51 patients (28%). At month 1 of treatment, viral persistence accurately predicted nonresponse (predictive value, 95.3; 95% confidence interval, 86.0-98.8; P < 0.0001). Independent predictors of sustained response were undetectable viremia at the first month of therapy (P < 0.001), undetectable viremia at the third month (P < 0.001), younger age (P = 0.006), nonsporadic infection (P = 0.012), and higher pretreatment aspartate aminotransferase levels (P = 0.032). In patients who cleared HCV RNA at month 1 of therapy, the predicted probability of sustained response averaged 70% for those younger than 30 years and diminished by 10% for each decade of age. CONCLUSIONS: Failure to clear HCV RNA at month 1 of treatment is strongly and independently associated with a very low probability of a sustained response to interferon.

Adolescent↗
PubMed1997

Surgical infections and prophylactic antibiotics: 341 consecutive cases of gallbladder surgery in the era of laparoscopic surgery.

HYPOTHESIS: This study was undertaken to assess the use of prophylactic antibiotics (PA) in laparoscopic and open cholecystectomy with respect to the postoperative infection rate and the established criteria for PA use. METHODS: A total of 341 consecutive cases for 1994 were retrospectively analyzed. PA use was deemed appropriate if the patient: was over 70 years of age, had common duct stones, jaundice, or acute cholecystitis. RESULTS: The infection rate of patients having an open cholecystectomy was significantly greater than the laparoscopic group (12.9% versus 1.8%, p < .001). In the laparoscopic group of patients who met the criteria for PA and received PA there were no infections as compared with those who had criteria for but did not receive PA (0% versus 22%, p < .05). Only 27% of all elective cholecystectomy patients received cefazolin while 73% of patients received extended spectrum antibiotics. CONCLUSIONS: In 63.2% of patients antibiotics were used with no indication for PA. In 73% of patients, an extended spectrum drug was used when a less expensive and narrower spectrum agent would have sufficed. Open cholecystectomy has a significantly higher infectious rate than closed cholecystectomy.

Antibiotic Prophylaxis↗
PubMed1997

Quality of life in breast cancer. Part I: Physical and social well-being.

Almost 2 million breast cancer survivors reside in the United States. An increase in consumer advocacy and media attention to this disease has helped bring breast cancer survivorship to the forefront of public attention. This has led to increased attention on quality of life (QOL) issues for these survivors of breast cancer. This two-part article presents the results of a qualitative, descriptive study evaluating the QOL of 21 breast cancer survivors. This study is based on our conceptual model of QOL including physical, psychological, social, and spiritual well-being. Part I of this article describes the impact of breast cancer on the physical and social domains of QOL based on in-depth interviews with breast cancer survivors.

Breast Neoplasms↗
PubMed1997

Open heart operations without transfusion using a multimodality blood conservation strategy in 50 Jehovah's Witness patients: implications for a "bloodless" surgical technique.

BACKGROUND: Blood transfusion persists as an important risk of open heart operations despite the recent introduction of a variety of new pharmacologic agents and blood conservation techniques as independent therapies. A comprehensive multimodality blood conservation program was developed to minimize this risk. STUDY DESIGN: To provide a strategy for operating without transfusion, this program was prospectively applied to 50 adult patients who are Jehovah's Witnesses and have undergone open heart operation at our institution since 1992. The blood conservation program used for these patients included the use of high-dose erythropoietin (800 U/kg load, 500 U/kg every other day), aprotinin (6 million U total dose full Hammersmith regimen), "maximal" volume intraoperative autologous blood donation, intraoperative cell salvage, continuous shed blood reinfusion, and drawing as few blood specimens as possible. RESULTS: Procedures performed included first-time coronary bypass operations (n = 30) and more complex operations, including reoperations, valve replacements, and multiple valve replacements with or without coronary bypass (n = 20). Despite the absence of transfusion, the mean discharge hematocrit in these patients was greater than 30 percent, and there was no anemia-related mortality rate in this group. The overall in-hospital mortality for the group was 4 percent. A subset analysis was performed between the 30 first-time coronary bypass patients (group 1) and a control group of 30 consecutive patients who were not Jehovah's Witnesses but had undergone first-time coronary bypass during the same period (group 2). The blood conservation program described in the previous paragraph was not used in group 2 patients and specific transfusion criteria were prospectively applied. The chest tube output in group 1 patients was less than 40 percent of that for group 2 patients at all points measured after operation (p < 0.01). Postoperative hematocrit levels in group 1 were greater than those for group 2, despite the absence of red blood cell transfusion and despite a significantly lower admission hematocrit and red blood cell mass in group 1. The average length of stay and ancillary costs for the two groups were equivalent. Although group 1 and 2 patients were well matched for preoperative transfusion risk factors, none of the group 1 patients required transfusion, but 17 (57 percent) group 2 patients met transfusion criteria and received 3.0 +/- 4.8 U (mean plus or minus standard deviation) of homologous blood or blood products. CONCLUSIONS: These results suggest that even complex open heart operations can be performed without homologous transfusion by optimally applying available blood conservation techniques. More generalized application of these measures may increasingly allow "bloodless" operations in all patients.

Adult↗
PubMed1997

Are the laboratory and field conditions observations of acute mountain sickness related?

In order to study relationships between acute mountain sickness (AMS) observations done both during a short-term hypoxic exposure in a hypobaric chamber, and in field conditions during a high altitude expedition, nine subjects were submitted to a 9-h hypoxic exposure in a hypobaric chamber. Then, they experienced a high altitude expedition in the Himalayas. The Lake Louise AMS scoring system was used to assess AMS in both conditions, especially the self report questionnaire. During the expedition, the mean self report score of each subject, defined as the ratio between the sum of daily self report scores and the duration of the expedition, appears to be correlated not only to the maximal self report score observed in altitude (r = +0.77, p < 0.05) but also to the self report and self report+clinical assessment scores observed at the end of the hypobaric chamber sojourn (r = +0.81, p < 0.01 and r = +0.75, p < 0.05, respectively). In conclusion, the Lake Louise AMS scoring system, especially the self report questionnaire, is relevant to assess AMS with simplicity and rapidity both in laboratory and in field conditions. Our study also suggests that AMS induced by a short term sojourn in a hypobaric chamber is related to AMS observed in field conditions.

Acute Disease↗
PubMed1996

Tumor necrosis factor alpha gene expression and the response to interferon in chronic hepatitis C.

Tumor necrosis factor alpha (TNF-alpha) is a cytokine with pleiotropic properties that is induced in a variety of pathological situations including viral infections. In this work, we analyzed the expression of TNF-alpha gene in patients with chronic hepatitis C. Serum TNF-alpha levels were found to be elevated in all chronic hepatitis C patients including those cases presenting sustained biochemical remission of the disease after interferon therapy. Untreated patients with chronic hepatitis C showed increased TNF-alpha messenger RNA (mRNA) levels in the liver and mononuclear cells as compared with healthy controls. After completion of treatment with interferon, patients experiencing sustained complete response showed values of TNF-alpha mRNA, both in the liver and in peripheral mononuclear cells, within the normal range, significantly lower than patients who did not respond to interferon and than those with complete response who relapsed after interferon withdrawal. Pretreatment values of TNF-alpha mRNA were lower in long-term responders to interferon than in cases who failed to respond to the treatment. Values of TNF-alpha mRNA in the liver or in mononuclear cells were higher in specimens with positive hepatitis C virus (HCV) RNA than in those samples where the virus was undetectable. Neither the intensity of the liver damage nor the amount of HCV RNA in serum or in cells showed correlation with the levels of TNF-alpha transcripts in peripheral mononuclear cells but it was found that high TNF-alpha values were associated with genotype 1b. In conclusion, there is an enhanced expression of TNF-alpha in HCV infection. High levels of this cytokine may play a role in the resistance to interferon therapy.

Adult↗
PubMed1996

Pre-adaptation, adaptation and de-adaptation to high altitude in humans: cardio-ventilatory and haematological changes.

The aim of this study was first to investigate cardio-ventilatory and haematological responses induced by intermittent acclimation and second to study de-adaptation from high altitude observed after descent. To achieve these objectives nine subjects were submitted to intermittent acclimation in a low barometric chamber (8 h daily for 5 days, day 1 at 4500 m, day 5 at 8500 m) before an expedition to the Himalayas. Cardio-ventilatory changes were measured during a hypobaric poikilocapnic hypoxic test (4500 m, barometric pressure = 589 hPa) and haematological changes were studied at sea level. These measurements were performed before and after acclimation, after return to sea level, but also 1 and 2 months after the expedition. In addition, partial pressures of oxygen and carbon dioxide in arterial blood (PaO2, PaCO2) and arterial erythropoietin concentration [EPO] were measured at rest during the hypoxic test. Results suggested the pre-adaptation protocol was efficient since an increased PaO2 (+12%, P < 0.05), a smaller difference in alveolo-arterial PO2 ( -63%, P < 0.05) and a lower PaCO2 ( -11%, P < 0.05), subsequent to ventilatory changes, were observed after acclimation with a significant increase in reticulocytes and in sea level [EPO] (+44% and +62% respectively, P < 0.05). De-adaptation was characterized by a loss of these cardio-ventilatory changes 1 month after descent, whereas the haematological changes (increased red blood cells and packed cell volume, P < 0.05) persisted for 1 month before disappearing 2 months after descent. This study would also suggest that acute hypoxia performed after a sojourn at high altitude could induce significantly depressed EPO responses (P < 0.05).

Adaptation, Physiological↗
PubMed1995

Differential effects of monoclonal antibody blockade of adhesion molecules on in vivo susceptibility to soft tissue infection.

Leukocyte adherence to endothelial cells has been implicated in the pathogenesis of microvascular injury as well as in host defense against various infectious microorganisms. Administration of monoclonal antibodies directed against the beta chain of the leukocyte integrins inhibits leukocyte-endothelial-cell adherence and has been reported to modulate ischemia-reperfusion and inflammatory injury. However, such inhibition of adhesion molecule function adversely affects resistance to infection. The following studies were carried out to determine whether monoclonal antibodies to other adhesion molecules, including L-selectin (CD62L), and CD11a (the alpha chain of LFA-1), also increase susceptibility to infection. New Zealand White rabbits were shaved and given subcutaneous injections on their dorsa with 10(9) CFU of Staphylococcus aureus ATCC 25923 at two sites and with 10(8) CFU at two sites. A second set of rabbits were given subcutaneous injections with 10(8) CFU of P. aeruginosa ATCC 27853 at two sites and with 10(7) CFUs at two sites. The animals were monitored for 1 week. There were three blinded experimental groups: controls given saline and two groups given blocking monoclonal antibodies to either L-selectin (Dreg-200) or CD11a (R7.1). In contrast to monoclonal antibodies to CD18, none of the monoclonal antibodies significantly increased the risk of abscess formation by S. aureus, although inhibition of CD11a increased the rate of abscess formation by P. aeruginosa.

Abscess↗
PubMed1995

Evaluation of the Lake Louise acute mountain sickness scoring system in a hypobaric chamber.

This study evaluated the relevance of the Lake Louise acute mountain sickness (AMS) scoring system in comparison with other AMS scoring systems. To achieve this objective nine subjects were submitted to a 9-hr exposure to hypoxia in a hypobaric chamber (altitude 4500-5500 m) that led to the development of AMS. AMS was scored at the end of this exposure period both by questionnaires (Hackett AMS questionnaire, Lake Louise AMS self-report questionnaire, Environmental Symptoms Questionnaire ESQ II and ESQ IV) and by a clinical investigation following the Lake Louise AMS clinical and functional AMS assessment. The AMS scores were between 0 and 9 for the Hackett AMS score, 0 and 38 for the ESQ II AMS score, 0 and 13.7 for the ESQ IV AMS score, 0 and 10 for the Lake Louise AMS self-report, 0 and 2 for the Lake Louise AMS clinical assessment score, and between 0 and 2 for the Lake Louise functional score. All the AMS questionnaire scores were related to the clinical AMS assessment score (p < 0.05) without significant differences between them. The Lake Louise AMS self-report score appeared highly correlated to other AMS scoring systems (Hackett, ESQ II and ESQ IV) (p < 0.05). Suggestions were proposed to improve the sensitivity and the specificity of the Lake Louise AMS scoring questionnaire but also the Lake Louise AMS clinical assessment. In conclusion, this study suggests the relevance of the Lake Louise AMS self-report questionnaire to assess and score AMS with simplicity and rapidity.

Adult↗