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S Knox

Publications and source records attributed to S Knox.

12 recordsLinked to original sources
PubMed1992

Red cell filterability determined using the cell transit time analyzer (CTTA): effects of ATP depletion and changes in calcium concentration.

Cell transit time analysis (CTTA) is a new filtrometric technique for assessing red blood cell deformability by measuring the conductivity change caused by passage of erythrocytes through a polycarbonate filter. Most reported studies to date using CTTA have focused on the transit time (TT), the duration of passage of an individual red cell through a micropore. Bulk flow rate has not been previously measured via CTTA. The use of new enzyme based cleaning solutions make it possible to reduce clogging in micropore filters. Therefore, valid measures of the number of red cell transits per unit time (counts/s: C/S) can now be obtained. We evaluated both parameters, TT and C/S, as indicators of red cell filterability. Our goal was to evaluate the effect of metabolic changes shown by alternative techniques to affect red cell deformability. The two best established factors are changes in intracellular [ATP] and [Ca2+]. ATP depletion produces a very small increase in TT but a very marked decrease in C/S. In contrast, the addition of low concentrations of calcium produces an increase in TT with minimal decrease in C/S. The effects of calcium appear to be complex. The substantial changes in intracellular calcium induced by the ionophore A23187 result in a curvilinear pattern of increase in transit times and reduction in counts per s. Lanthanum, which inhibits egress of intracellular calcium, causes an increase in TT with a drop in C/S. We conclude that CTTA demonstrates the same changes in red cell deformability measurable by alternative filtrometric techniques; however, CTTA furnishes two separate and independent parameters which may be used to evaluate red cell deformability.

Adenosine Triphosphate↗
PubMed1992

Clinical utility of open lung biopsy for undiagnosed pulmonary infiltrates.

Open lung biopsy (OLB) is often performed as the definitive diagnostic procedure in patients with undiagnosed pulmonary infiltrates, but controversy exists as to the clinical utility of this practice. A retrospective review of 50 consecutive patients who underwent OLB for undiagnosed pulmonary infiltrates was done to assess the diagnostic value as well as the frequency with which these results affected therapy and mortality. Histologic tissue diagnoses were obtained in all patients. Specific pathologic diagnoses were obtained in 56% of patients, nonspecific in 44%. Lobar or lateralized infiltrates were more likely to yield a specific diagnosis (87%) than diffuse, bilateral infiltrates (42%). Thirty-four patients (68%) had previously had a nondiagnostic transbronchial biopsy; 58% of these patients had a specific diagnosis established by OLB. Twelve patients (24%) were in acute respiratory failure at the time of OLB; this group had a 50% mortality rate as compared with only 2.6% for patients not in acute respiratory failure (p less than 0.01). Therapy was altered (new specific or nonspecific treatment initiated or therapy withdrawn) in 78% of patients undergoing OLB. Thirty-day in-hospital survival was significantly higher in patients for whom either specific or nonspecific therapy was indicated and initiated versus those in whom no therapy was initiated or all therapy was withdrawn (mortality: 5.5% versus 35.7%; p = 0.01). Mortality was not related to the presence of immunosuppression or to the finding of a specific diagnosis. The overall mortality rate of 14% in this series compares favorably with mortality rates found in similar series, reflecting differences in patient populations and possibly the timing of intervention. OLB remains a clinically valuable diagnostic tool in selected patients.

Adult↗
PubMed1991

Effects of glycemic control on red cell deformability determined by using the cell transit time analyzer.

There is considerable evidence that blood viscosity is greater than normal in diabetes, and decreased red blood cell deformability has been suggested as the cause. However, viscosity can be influenced by changes in the properties of blood proteins in addition to red cells. Direct interpretation of red cell filtrometry data in terms of deformability has been complicated by the interfering effect of white cells and platelets and clogging of micropores. We have thus used the cell transit time analyzer, a new filtrometric procedure that eliminates these complications and produces an individual red cell micropore transit time profile, to reassess diabetic red cell deformability. Samples from 26 patients with diabetes and an equal number of subjects without diabetes who served as controls were assayed by the cell transit time analyzer at 2 and at 4 cm hydrostatic pressure. Samples from patients with diabetes and controls were sex and age matched for daily runs. At 2 cm H2O, red blood cell transit time for the patients with diabetes was 2.73 +/- 0.05 milliseconds as compared with 2.67 +/- 0.05 milliseconds for controls (p not significant). The ratio of transit time for patients with diabetes to that of controls (Td/Tnd) was 1.03 +/- 0.01 (p less than 0.05, Wilcoxon) at 2 cm H2O and 1.02 +/- 0.01 (p not significant) at 4 cm H2O.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Emotional coping and the psychophysiological substrates of elevated blood pressure.

A structured interview concerning emotional coping patterns was administered to 63 28-year-old men included in a psychophysiological study of blood pressure elevation. The interviews were tape recorded and subsequently evaluated by a rater not otherwise involved in the study. The interviews involved discussion of four emotions: anger, sorrow, anxiety, and joy. The results indicate that normotensives can express sorrow to significantly more people than hypertensives, and that their behavior in situations involving sorrow tends to be more instrumental than that of the group with labile pressure. Hypertensives also experienced significantly less joy than normotensives. In multiple regression analyses on physiological variables relevant for blood pressure elevation, the use of a somatic and unfocused way of describing sorrow was associated with significantly lower heart rate. The results show also that emotional coping explains a significant amount of the variance in three of the psychosocial functions involved in elevated blood pressure: ability to express anger at work, plus the social support variables of attachment and acquaintance.

Adaptation, Psychological↗
PubMed1986

Young men with high blood pressure report few recent life events.

Men who had high, medium and low blood pressure at age 18 (compulsory screening for military service in Stockholm) were examined ten years later at age 28. Interviewers, having had no information regarding past or present blood pressure, interviewed them about life events experienced during the year preceding the examination. Men with high blood pressure at rest reported fewer life events for the past year than other men. Furthermore, high plasma adrenaline levels at rest were associated with few reported life events.

Adolescent↗
PubMed1986

Stress management in the treatment of essential hypertension in primary health care.

The present study was a pilot project to determine the feasibility of a stress management program for treatment of hypertension in the Swedish primary health care system. Those patients in the catchment area of the primary health care center at Tumba hospital who were under 45 years old and diagnosed with primary hypertension during 1979-1981, were chosen to participate if they had had at least one measurement of 150 mmHg systolic and/or 95 mmHg diastolic during 1981. Patients on diuretic medication were included but those being medicated with beta-blockers were excluded for ethical reasons. Of the 21 people who fulfilled these criteria, 13 took part in the treatment, which lasted ten weeks. Both systolic and diastolic blood pressure decreased significantly (151.1 to 124.7 and 96.4 to 89.3, respectively). The conclusions drawn were that stress management may offer a viable alternative to medication of mild hypertension in primary health care and that it should be tested on a larger scale with systematic blood pressure measurements performed during daily activities, serving as a basis for baseline determination.

Adult↗
PubMed1985

Blood pressure variations during a working day at age 28: effects of different types of work and blood pressure level at age 18.

During an ordinary work day blood pressure was self-monitored once every hour in two samples of asymptomatic nonmedicating 28-year-old men. They were selected on the basis of previous compulsory blood pressure recordings made at the age of 18 when they had been drafted for military service. Subjects in the "original hypertensive sample" with "strain" occupations (hectic and uncontrollable, such as waiter, driver and cook) had more marked elevations of systolic blood pressure during work hours than other subjects.

Adult↗
PubMed1985

Psychosocial and physiological factors in relation to blood pressure at rest--a study of Swedish men in their upper twenties.

The interrelationships between psychosocial factors, several physiological variables and blood pressure (BP) were investigated in 88 young men (aged 26-32 years) in whom high, intermediate or low BP had been recorded at the age of 18 years. In the original high BP group, venous plasma noradrenaline was normal but adrenaline levels elevated. At the follow-up adrenaline correlated with systolic blood pressure (SBP), and this was also so after controlling for overweight and serum gamma-glutamyltranspeptidase [gamma-GT, a marker for alcohol consumption, which showed an independent association with diastolic blood pressure (DBP)]. Low assertiveness (low scores of verbal and indirect aggression) correlated with high BPs, even after controlling for other psychosocial variables. Several associations between psychosocial job variables and physiological variables were found. Among self-reported job variables, excessive 'demands' and 'bossing others' (but not 'decision latitude' or 'psychosocial conflict') were associated with high SBP. Habitual smoking of cigarettes was not associated with BP at rest, but influenced several associations between psychosocial and physiological variables. Men with high BP at rest and low plasma renin activity (PRA) reported more psychosocial problems at work and lower assertiveness than other groups.

Adult↗