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Biomedical subjects

N Lai

Publications and source records attributed to N Lai.

15 recordsLinked to original sources
PubMed2006

Relating pulmonary oxygen uptake to muscle oxygen consumption at exercise onset: in vivo and in silico studies.

Assessment of the rate of muscle oxygen consumption, UO(2m), in vivo during exercise involving a large muscle mass is critical for investigating mechanisms regulating energy metabolism at exercise onset. While UO(2m) is technically difficult to obtain under these circumstances, pulmonary oxygen uptake, VO(2p), can be readily measured and used as a proxy to UO(2m). However, the quantitative relationship between VO(2p) and UO(2m) during the nonsteady phase of exercise in humans, needs to be established. A computational model of oxygen transport and utilization--based on dynamic mass balances in blood and tissue cells--was applied to quantify the dynamic relationship between model-simulated UO(2m) and measured VO(2p) during moderate (M), heavy (H), and very heavy (V) intensity exercise. In seven human subjects, VO(2p) and muscle oxygen saturation, StO(2m), were measured with indirect calorimetry and near infrared spectroscopy (NIRS), respectively. The dynamic responses of VO(2p) and StO(2m) at each intensity were in agreement with previously published data. The response time of muscle oxygen consumption, tauUO(2m) estimated by direct comparison between model results and measurements of StO(2m) was significantly faster (P < 0.001) than that of pulmonary oxygen uptake, tauVO(2p) (M: 13 +/- 4 vs. 65 +/- 7 s; H: 13 +/- 4 vs. 100 +/- 24 s; V: 15 +/- 5 vs. 82 +/- 31 s). Thus, by taking into account the dynamics of oxygen stores in blood and tissue and determining muscle oxygen consumption from muscle oxygenation measurements, this study demonstrates a significant temporal dissociation between UO(2m) and VO(2p) at exercise onset.

Adolescent↗
PubMed2004

Search for the rare decay K(L)-->pi(0)e(+)e(-).

The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay K(L)-->pi(0)e(+)e(-). This mode is expected to have a significant CP violating component. The measurement of its branching ratio could support the standard model or could indicate the existence of new physics. This Letter reports new results from the 1999-2000 data set. One event is observed with an expected background at 0.99+/-0.35 events. We set a limit on the branching ratio of 3.5x10(-10) at the 90% confidence level. Combining with the previous result based on the data set taken in 1997 yields the final KTeV result: BR(K(L)-->pi(0)e(+)e(-))<2.8x10(-10) at 90% C.L.

Journal Article↗
PubMed2003

Measurements of the Decay KL-->e+ e- mu+ mu-.

The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined to be [2.69+/-0.24(stat)+/-0.12(syst)]x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.

Journal Article↗
PubMed2000

The effects of dietary supplementation with isoflavones from red clover on the lipoprotein profiles of post menopausal women with mild to moderate hypercholesterolaemia.

The effects of dietary isoflavone supplementation using a purified extract of red clover containing approximately biochanin A 26 mg, formononetin 16 mg, daidzein 0.5 mg and genistein 1 mg per tablet at doses of one or two tablets per day were compared to placebo in a three-period, randomised, double blind, ascending dose study in 66 post menopausal women with plasma cholesterol levels between 5.0 and 9.0 mmol/l. Each treatment period lasted 4 weeks and a further nine women received placebo for the full 12-week period. All women consumed a low isoflavone diet for 2 weeks preceding the commencement of the study and for the 12-week study period. Urinary isoflavone excretion was very low in subjects receiving placebo but increased in a dose-dependent manner during therapy with one and two of isoflavone tablets. Dietary supplementation with isoflavones did not significantly alter total plasma cholesterol, LDL cholesterol, HDL cholesterol or plasma triglyceride levels. However, inverse correlations were found between urinary genistein excretion and plasma triglyceride levels and between urinary O-DMA excretion (an isoflavone metabolite) and plasma triglyceride levels in subjects receiving one isoflavone tablet, suggesting a weak relationship between isoflavone intake and plasma triglycerides which may be influenced by individual differences in isoflavone absorption or metabolism. The results suggest that isoflavone phytoestrogens from red clover in the proportions and quantities studied do not significantly alter plasma lipids in post menopausal women with moderately elevated plasma cholesterol levels.

Aged↗
PubMed2000

Enhanced peripheral vasodilation in humans after a fatty meal.

OBJECTIVES: We sought to study the effects of a fatty meal on vascular reactivity, including endothelial function and maximal vasodilation. BACKGROUND: Recent reports regarding the physiological changes in peripheral vasculature after eating a fatty meal have been controversial. METHODS: Twelve volunteers were studied before, 3 h after, and 6 h after a high-fat meal (1030 kcal, 61 g fat) rich in saturated fatty acids, and 10 were restudied after a similar meal rich in monounsaturated fatty acids. Endothelial function was assessed as flow-mediated dilatation (FMD) in the brachial artery using ultrasound. Resting and postischemic forearm blood flow (FBF) were recorded using venous occlusion strain-gauge plethysmography, before, and every 10 to 15 s after, 5 min upper arm ischemia. RESULTS: Brachial artery basal diameter, resting FBF and postischemic hyperemia increased after high-fat meals (all p<0.001), whereas FMD did not change. The increase in resting FBF correlated with increases in postprandial insulin (r = 0.80, p<0.002) and triglyceride (r = 0.77, p<0.005) levels. CONCLUSIONS: We concluded that eating a fatty meal induces vasodilation and increases resting and stimulated FBF and that these observations are probably mediated by postprandial changes in insulin and/or triglyceride levels. The metabolic changes that occur after meals are not associated with impaired endothelial nitric oxide release in the conduit arteries.

Adolescent↗
PubMed1999

Trends in the incidence, severity, and short-term outcome of stroke in perth, Western Australia.

BACKGROUND AND PURPOSE: This report describes trends in the key indices of cerebrovascular disease over 6 years from the end of the 1980s in a geographically defined segment of the city of Perth, Western Australia. METHODS: Identical methods were used to find and assess all cases of suspected stroke in a population of approximately 134 000 residents in a triangular area of the northern suburbs of Perth. Case fatality was measured as vital status at 28 days after the onset of symptoms. Data for first-ever strokes and for all strokes for equivalent periods of 12 months in 1989-1990 and 1995-1996 were compared by age-standardized rates and proportions and Poisson regression. RESULTS: There were 355 strokes in 328 patients and 251 first-ever strokes (71%) for 1989-1990 and 290 events in 281 patients and 213 first-ever strokes (73%) for 1995-1996. In Poisson models including age and period, overall trends in the incidence of both first-ever strokes (rate ratio=0.75; 95% confidence limits, 0.63, 0.90) and all strokes (rate ratio=0.73; 95% confidence limits, 0.62, 0.85) were obviously significant, but only the changes in men were independently significant. Case fatality did not change, and the balance between hemorrhagic and occlusive strokes in 1995-1996 was almost indistinguishable from that observed in 1989-1990. CONCLUSIONS: Our results, which are the only longitudinal population-based data available for Australia for key indices of stroke, suggest that it is a change in the frequency of stroke, rather than its outcome, that is chiefly responsible nationally for the fall in mortality from cerebrovascular disease.

Adolescent↗
PubMed1998

Nursery practices and detection of jaundice after newborn discharge.

OBJECTIVE: To investigate nursery practices regarding outpatient recognition of neonatal jaundice. DESIGN: Descriptive survey. PARTICIPANTS: Random sample of nursery head nurses and pediatricians from national lists. SETTING: Nurseries with more than 100 births per year and pediatricians responsible for newborn discharges. RESULTS: Head nurses from 204 nurseries and 200 pediatricians were surveyed, with 62% of head nurses and 55% of pediatricians responding. Almost half of the head nurses (45%) reported lack of a written neonatal jaundice protocol. Twenty-seven percent of head nurses and pediatricians reported that no system is in place to track jaundiced newborns after discharge. Forty percent of head nurses and 26% of pediatricians reported from higher-risk nurseries, defined as nurseries where more than 25% of mothers did not have a high school diploma or more than 50% of infants were born to single-parent families. These nurseries were no more likely to have a protocol for jaundice management or to use a system to track newborns after discharge. Discharge of most newborns before 36 hours of age was common (70% of head nurses, 62% of pediatricians) and some respondents discharged most newborns before 24 hours of age (16% of head nurses, 12% of pediatricians). For newborns discharged before 24 hours of age, more than half of the nurseries surveyed scheduled follow-up within 2 to 3 days (53% of head nurses, 62% of pediatricians). The likelihood of such follow-up did not differ by type of health care insurance, level of maternal education, percentage of single-parent families, predominance of minority patients, or higher risk as defined above. CONCLUSIONS: In our sample, many nurseries lack parent education, neonatal jaundice protocols, and neonatal jaundice tracking systems. Newborns discharged before 48 hours of age are often not scheduled to be seen by a health care provider within 2 to 3 days, despite American Academy of Pediatrics guidelines recommending such follow-up.

Continuity of Patient Care↗
PubMed1995

The transition to air breathing in fishes. V. Comparative aspects of cardiorespiratory regulation in Synbranchus marmoratus and Monopterus albus (Synbranchidae)

Extreme heart-rate lability accompanies the air-breathing cycles of Synbranchus marmoratus and Monopterus albus. When air is taken into the buccopharyngeal air-breathing organ of these fishes, heart rate increases sharply above pre-inspiration rates of 3&shy;25 beats min-1 to as high as 40&shy;45 beats min-1. With time, and as O2 is depleted from the air-breathing organ, heart rate gradually declines and drops to its lowest level with, or following, exhalation. Relationships between air breathing and sinus arrhythmia in M. albus were investigated by injecting variable gas volumes and O2 mixtures into the cannulated air-breathing organ. Tests were also carried out on undisturbed fish breathing volitionally in atmospheres containing different O2 levels. Both the volume and O2 content of the inspired gas affect the level and duration of inspiration tachycardia. Additional factors affecting tachycardia are the heart rate prior to inspiration and the time since air was last held. S. marmoratus is a non-obligatory air breather and uses rhythmic branchial aquatic respiration to a greater extent than M. albus, an obligate air breather. While the heart rates of both species are increased during aquatic ventilation, the higher heart rate to ventilation ratio in S. marmoratus (2&shy;3 versus approximately 1 in M. albus) seems attributable to its more proficient aquatic respiratory system. The available cardiorespiratory data for air-breathing fishes indicate that the scope of air-inspiration tachycardia is smaller in lungfishes and other primitive species than in most teleosts. This difference is mainly attributable to the greater chronotropic effect of sympathetic cardiac innervation in teleosts.

Journal Article↗
PubMed1995

Wolff-Parkinson-White syndrome and radiofrequency ablation.

Wolff-Parkinson-White syndrome is the most common of the preexcitation syndromes and is due to an accessory pathway connecting the atria and ventricles. Asymptomatic patients do not require empirical therapy. Ongoing drug therapy has traditionally been the choice for older symptomatic patients and patients with infrequent symptoms. However, more definitive therapy, ie, surgical or nonsurgical ablation, may be preferable for younger patients, patients with medically refractory arrhythmias, and patients at high risk for sudden death. Ablation by radiofrequency current is now being routinely performed because it appears to be cost-effective and has been found to be safe and efficient if performed by skilled operators. Clinical experience of this procedure is limited, however, and long-term effects still need to be established.

Adult↗
PubMed1989

[Angiomyolipoma of the kidney: a case of spontaneous rupture].

After reporting the general features of renal angiomyolipoma (AML), either isolated or associated to other conditions (Bourneville sclerosis, Wunderlich's syndrome), the Authors discuss a case complicated by perirenal spontaneous hematoma, undergone emergency operation (simple nephrectomy). At a 3 year follow-up the patient is in good general and local conditions (negative TC, normal renal function, preexistent hypertension disappeared). Literature is reviewed and some considerations about diagnosis and surgical tactics are reported.

Adult↗
PubMed1987

Female genital cancer incidence in the Province of Sassari from 1974 to 1983.

The incidence of gynaecologic tumours in the Province of Sassari has been studied in order to estimate their value and to make a comparison with the ones industrialised countries. The global incidence of uterine cancer (corpus uteri plus cervix) is of 18.16/100,000 women; 11.99/100,000 for cancers of corpus uteri and 6.17/100,000 for cervical carcinoma including in situ forms. The incidence of gynaecologic tumors for the District of Sassari is equivalent to that reported in Western countries and it does confirm indeed a constant and progressive increase in tumours of the corpus uteri and a reduction in cervical carcinoma especially if in situ forms are excluded.

Adolescent↗
PubMed1985

Diagnosis of hydatid cyst by percutaneous aspiration: value of electrolyte determinations.

A study was made of the fluid from 11 hydatid cysts (10 hepatic, one renal) and from 50 nonparasitic cysts (25 renal, 10 ovarian, 10 pancreatic and five hepatic). Our analysis indicated that the chloride (range 62-95 mEq/liter), the sodium (range 125-139 mEq/liter) and the potassium content (range 5.1-7.5 mEq/liter) of the former differed significantly (p less than 0.01) from those of the controls. Hydatid cysts may be indistinguishable from others with both CT and ultrasound and therefore the electrolyte data are of diagnostic value when a hydatid cyst is accidentally punctured percutaneously.

Biopsy, Needle↗
PubMed1983

Evaluation of peritoneovenous shunt patency with Tc-99m labeled microspheres.

The LeVeen peritoneovenous shunt (PVS) was investigated in 40 cirrhotic patients with refractory ascites. Five millicuries of Tc-99m-tagged human albumin microspheres (15-36 microns) were injected into the peritoneal cavity between the umbilicus and the left anterior superior iliac spine. The radiotracer was always detectable by scintigram in the lungs when the shunt was patent. In case of malfunction, by contrast, the radioactivity was either restricted to the venous tube or confined below the diaphragm for at least 4 hr. In the presence of complete obstruction, whereas the tube was not visualized after peritoneal injection, it was outlined by direct injection of 2 mCi of Tc-99m albumin microspheres into its subcutaneous tract, where it crossed the 12th rib, immediately above the valve. This technique sufficed to establish whether the site of obstruction was at the valve or in the tubing itself. In one patient, poor visualization of the tube and a delayed image of the lungs was caused by partial occlusion of the valve with fibrinoid debris. This radiotracer method proved simple, quick, and led to an immediate selective replacement when the shunt was not patent. Therefore, the use of this test is recommended for a definitive diagnosis, since there were neither false negatives nor false positives. No complications such as embolism or bacterial infection were encountered with Tc-99m human albumin microspheres, which are excellent tracers.

Adult↗
PubMedDate not supplied

[Postoperative infections: the use of thymostimulin (TP1) in patients at risk].

The authors report data related to 212 surgical patients at risk because immunocompromised. Patients were divided in two homogeneous groups, one treated with Thymostimulin and the other as a control group, all affected by severe pathologies. Patients presenting postoperative complications directly related to technical reasons were excluded. Morbidity, postoperative hospitalization and mortality were the parameters considered. Positive results were obtained in the treated group compared to controls. Therefore, it is Authors' opinion that the treatment with Thymostimulin in immunocompromised patients is important in order to avoid or reduce postoperative infection rates.

Adjuvants, Immunologic↗