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Biomedical subjects

L Kirk

Publications and source records attributed to L Kirk.

At least 19 recordsLinked to original sources
PubMed2004

Malt sprout extract medium for cultivation of Lactobacillus plantarum protective cultures.

AIMS: The aim was to develop a cheap cereal-based alternative medium for the large-scale production of biopreservative Lactobacillus plantarum VTT E-79098. We examined the effect of growth medium and pH control on the cell yield of Lact. plantarum E-79098 and the antimicrobial activity of the cell-free extracts. METHODS: Fermentations using a novel Malt Sprout Extract Medium (MSE) were performed with different pH regimes. The antimicrobial activity of the cell-free extracts against Pantoea agglomerans VTT E-90396 and Fusarium avenaceum VTT D-80147 was assessed with automated turbidometry. SIGNIFICANCE AND IMPACT OF THE STUDY: When compared with MRS, the MSE medium cultures produced equal growth yields of Lact. plantarum VTT E-79098 and enhanced antimicrobial potential against the Gram-negative bacterium P. agglomerans and a Fusarium fungus. The MSE medium can be used as a low-cost alternative to MRS for producing high cell yields and good antimicrobial activity of Lact. plantarum.

Anti-Bacterial Agents↗
PubMed2000

An evaluation of stress symptoms associated with academic sexual harassment.

It is clear that sexual assault can precipitate posttraumatic stress disorder. Some theorists have suggested that less severe sexually harassing behaviors may also have trauma-like sequelae. In a study evaluating this hypothesis, 69 female participants completed self-report measures of instances of sexual harassment, basic beliefs, psychological distress/symptoms, and PTSD symptoms. Participants watched videotapes depicting sexual harassment, emotional arousal (not sexual in nature), and a neutral interaction while their heart rate was monitored, and they were interviewed using the SCID for PTSD. Results revealed that those who had been sexually harassed reported more negative basic beliefs, more general distress, and more negative state mood after watching the sexual harassment video, relative to those who had not been harassed. The severity of sexual harassing behaviors experienced was positively correlated with PTSD symptoms. Heart rate reactivity to the videotapes did not differ across groups defined by sexual harassment status.

Adult↗
PubMed1999

Experiences of anger in people who have recovered from depression and never-depressed people.

Previous research has linked anger suppression with depression. This study extended prior research by comparing people who had recovered from a major depression (RD) with those who had never been depressed (ND). The RD group significantly exceeded the ND group in the degree to which they reported holding anger in and being afraid to express it. Also, RD participants were more likely to endorse attitudes consistent with silencing the self theory, believing they must hide their feelings to preserve relationships. They were also more likely to have experienced an anger attack. Both silencing the self and a history of anger attacks were significantly correlated with fear of anger expression; future longitudinal or experimental studies are needed to determine whether these variables play a causal role in anger inhibition and in recurrence of depression.

Adaptation, Psychological↗
PubMed1998

Priming irrational beliefs in recovered-depressed people.

Major depression has been linked with endorsement of irrational beliefs in cross-sectional research, consistent with the rational emotive behavior therapy (REBT) model. In this study, the authors extended prior research by using multiple measures of irrationality and by comparing never-depressed (ND) controls with people who had recovered from major depression. Contrary to the REBT model, the recovered-depressed (RD) group did not significantly exceed the ND group in irrational beliefs before, during, or after exposure to simulated stressful situations. However, associations between irrationality and negative mood, and to a lesser extent between situation-specific irrationality and personality vulnerabilities, were obtained in the RD group but not in the ND group. These findings are consistent with the possibility that RD persons on average may be especially susceptible to having irrationality primed by negative mood states or by the important setbacks that can lead to such mood states.

Adult↗
PubMed1998

A controlled trial of venlafaxine in trichotillomania: interim phase I results.

This article reports the preliminary findings of a two-phase trial examining the efficacy of venlafaxine in trichotillomania. Phase 1 is a 12-week, open-label, prospective trial of venlafaxine in trichotillomania. Venlafaxine was effective in significantly reducing the symptoms of trichotillomania; 8 of 12 patients were considered responders. The implications of the efficacy of venlafaxine in trichotillomania are discussed, including its important advantages over other available antidepressant and anxiolytic medications.

Adult↗
PubMed1993

Zymomonas mobilis--science and industrial application.

Zymomonas mobilis is undoubtedly one of the most unique bacterium within the microbial world. Known since 1912 under the names Termobacterium mobilis, Pseudomonas linderi, and Zymomonas mobilis, reviews on its uniqueness have been published in 1977 and 1988. The bacterium Zymomonas mobilis not only exhibits an extraordinarily uniqueness in its biochemistry, but also in its growth behavior, energy production, and response to culture conditions, as well as cultivation techniques used. This uniqueness caused great interest in the scientific, biotechnological, and industrial worlds. Its ability to couple and uncouple energy production in favor of product formation, to respond to physical and chemical environment manipulation, as well as its restricted product formation, makes it an ideal microorganism for microbial process development. This review explores the advances made since 1987, together with new developments in the pure scientific and applied commercial areas.

Carbohydrate Metabolism↗
PubMed1992

The effects of sodium bicarbonate and pyridoxine-alpha-ketoglutarate on short-term maximal exercise capacity.

The purpose of this study was to determine the effects of the simultaneous use of pyridoxine-alpha-ketoglutarate (PAK) and sodium bicarbonate (NaHCO3) on short-term maximal exercise capacity in eight well-trained male cyclists. The study consisted of the determination of maximal power output and the administration of various combinations of placebos, PAK and NaHCO3, followed by a short-term maximal exercise test. To determine maximal power output (power(max)), the subjects performed a continuous, incremental test on a Monark bicycle ergometer to symptom limited maximum (test 1). To determine the effects of NaHCO3 and PAK on short-term maximal exercise performance, the subjects were administered either placebo (PLA), PAK and sodium bicarbonate (P/B), PAK and placebo (PAK), or sodium bicarbonate and placebo (BIC) prior to performing short-term maximal exercise (test 2). Oral tablets of NaHCO3 and PAK were given in doses of 200 mg kg-1 and 50 mg kg-1 respectively. The subjects pedalled at the power output corresponding to 100% of their VO2 max at 70 rev min-1 until voluntary cessation or until they were unable to maintain pedal revolution rate. Venous blood samples were drawn at rest (RES), cessation of exercise (CES) and after 2 min of recovery (REC) and analysed for lactate, pH and bicarbonate ion concentration. The subjects attained an average maximum power output of 377 +/- 20 W during the graded maximal pre-test (test 1). There were no significant differences between treatments in the ability to sustain power(max) during test 2. During test 2, the subjects were able to sustain power(max) for 7.6 +/- 4.3 min with P/B, 6.7 +/- 2.9 min with PAK, 7.3 +/- 4.9 min with BIC and 6.9 +/- 2.7 min with placebo (mean +/- S.E.). Blood lactate (BLa) was significantly elevated at cessation of exercise and remained elevated during recovery, but there were no significant differences between treatments. Bicarbonate fell significantly during exercise and recovery in each treatment. At rest, bicarbonate levels were significantly higher in both the P/B and BIC than in the PAK or PLA treatments. Pooled data from the P/B and BIC treatments demonstrated a significant increase in pH at rest and end of exercise when compared to PLA treatment. These data suggest that sodium bicarbonate rather than PAK was responsible for this increase. In summary, our data suggest that in the dosages used in this study, administration of sodium bicarbonate or PAK, alone or in combination, is ineffective in increasing short-term maximal exercise capacity.

Adult↗
PubMed1990

A comparison of blood gases and acid-base measurements in arterial, arterialized venous, and venous blood during short-term maximal exercise.

The purpose of this study was to determine the relationship between blood gases and acid-base measurements in arterial, arterialized venous, and venous blood measured simultaneously during short-term maximal exercise. Ten well-trained male cyclists performed a graded maximal exercise test on a cycle ergometer to determine the power output corresponding to their peak oxygen consumption (test I), and a short-term maximal test on a cycle ergometer at peak power output (test II). During test II arterial, arterialized venous and venous blood were sampled simultaneously for determination of partial pressures of oxygen and carbon dioxide, pH, bicarbonate (HCO3-), base excess (BE), and lactate (La). Samples were taken at rest, the end of 1 min of exercise (1 ME), at the end of exercise (EE), and at 2 min of recovery (REC). During test II, subjects maintained a peak power output of 370.6 (62.1) W [mean (SD)] for 4.5, SD 1.6 min. Except at rest venous and arterialized venous measurements tended to be the same at all sampling intervals, but differed significantly from measurements in arterial blood (P less than 0.05). BE was the only variable that rendered consistently significant correlations between arterial and arterialized venous blood at each sampling interval. The pooled correlation coefficient between arterial and arterialized venous BE was r = 0.83 [regression equation: BEa = (0.84 BEav)-0.51]. Arterial La was significantly higher than venous La at 1 ME (2.8, 0.7 vs 0.8, 0.3 mmol.l-1) and higher than both venous and arterialized venous La at EE.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Plasma tyrosine/neutral amino acid ratio correlated with clinical response to nortriptyline in endogenously depressed patients.

Ratios in plasma of tryptophan (Trp) and tyrosine (Tyr) to other large neutral amino acids were determined in 26 endogenous depressives before and after treatment with nortriptyline in doses adequate to achieve a steady-state serum level between 70 and 130 ng/ml, i.e., within the recommended therapeutic range. Pretreatment plasma Trp ratio and Tyr ratio were normal and did not change significantly during treatment. The plasma Trp and Tyr concentrations and the plasma Trp ratio showed no significant association with the therapeutic response. However, the pretreatment plasma Tyr ratio correlated significantly and directly with the final Hamilton rating score, and inversely with the per cent reduction of Hamilton rating score. Moreover, depressives with plasma Tyr ratio below the normal mean showed significantly greater clinical improvement than patients with higher plasma Tyr ratio with comparable serum nortriptyline levels. Evidence has been presented that biochemical variables in depressed patients are important determinants of clinical improvement following pharmacotherapeutic treatment. Moreover, the results suggest that the plasma Tyr ratio may be a guideline for antidepressant response to nortriptyline.

Adult↗
PubMed1983

Serum concentrations of the isomers of clopenthixol and a metabolite in patients given cis(Z)-clopenthixol decanoate in viscoleo.

Cis(Z)-clopenthixol decanoate in Viscoleo (Sordinol Depot, Cisordinol Depot, Clopixol Inj.) was given intramuscularly to nine schizophrenic patients with dosage intervals of 1 or 2 weeks. Serum concentrations of the two geometric isomers of clopenthixol and its N-dealkyl metabolite were recorded in two successive dosage intervals. Significant correlations were found for dose vs area under the serum concentration curve and vs serum concentrations measured on individual days. The last mentioned concentrations are good measures of the area under the serum concentration curve, which expresses the drug load of the patient. The serum concentration curves in two successive dosage intervals were very similar. Maximum serum concentration was seen 5-7 days after injection and the mean maximum/minimum fluctuation was 1.6 with the 2-week dosage interval. The finding of very low amounts of the trans(E)-isomers of clopenthixol and the N-dealkyl-metabolite shows that isomerization of the cis(Z)-compounds into the corresponding trans(E)-isomers does not take place within the organism.

Adult↗
PubMed1983

Further studies on the hypernoradrenergic state of treated hypertensives: effect of captopril.

We investigated the effect of captopril on plasma norepinephrine concentration and blood pressure in two groups of hypertensive patients. One group consisted of five severely hypertensive patients rendered hypernoradrenergic by administration of a minoxidil-propranolol-diuretic regimen. The other group was ten untreated mildly hypertensive patients. Two hours after 12.5mg of captopril, blood pressure was lowered (p less than .05) in four of the five hypernoradrenergic patients from 180 +/- 8/102 +/- 8 to 132 +/- 7/77 +/- 8 mmHg. Chronic administration of 100-150mg of captopril tid caused no further blood pressure reduction. Precaptopril plasma norepinephrine concentration was 925 +/- 206 and two hours after the 12.5mg dose was 807 +/- 80 pg/ml. Three months later having advanced the dose to 300-450 mg/day it was lower (p less than .05) at 752 pg/ml. The acute blood pressure response correlated (r = -0.72, p less than .001) with the precaptopril plasma norepinephrine. Precaptopril blood pressure in the mild hypertensive patients was 146 +/- 4/98 +/- 1, after a 25-100mg dose it was 137 +/- 6/91 +/- 2 (diastolic p less than .05) and at two months with the same captopril dose bid it was 141 +/- 8/88 +/- 4 mmHg (diastolic p less than .01). Corresponding initial PNE was 425 +/- 72, two hours after captopril 405 +/- 47 and 310 +/- 63 pg/ml (p less than .05) with chronic administration. Thus, captopril lowers blood pressure in both hypernoradrenergic and eunoradrenergic hypertensive patients without increasing plasma norepinephrine suggesting some unique dampening effect of this drug on the sympathetic nervous system. Also, addition of captopril to triple therapy lowered blood pressure in proportion to plasma norepinephrine levels suggesting importance to its action on this sympathetic nervous system effector.

Blood Pressure↗
PubMed1982

Tryptophan tolerance and metabolism in endogenous depression.

The concentration of free and total tryptophan and kynurenine in plasma from 49 female depressives and 26 female controls was measured following oral loading with L-tryptophan, 100 mg/kg body weight. There was no significant difference between five depressives and six controls in the area under curve for free or total tryptophan or kynurenine in plasma. The peak concentration of kynurenine occurred 4 h after loading and in correlated significantly with the area under curve for kynurenine. There was no significant correlation between the L-tryptophan dose (g) and the plasma concentration of kynurenine a 4 h in the 49 depressives or 26 controls. The mean plasma levels of tryptophan and kynurenine at 4 h in the depressives were not significantly different from control levels. There was no clear relationship between the plasma levels of tryptophan or kynurenine at 4 h and the therapeutic response in 13 depressives treated with L-tryptophan for 15 days. It is concluded that the absorption, the plasma clearance, and the degradation to kynurenine of loading doses of L-tryptophan are normal in depressed patients. Results furthermore suggest that the plasma levels of tryptophan and kynurenine at 4 h are poor predictors of the response to L-tryptophan treatment in depressives.

Adult↗
PubMed1980

Concentrations of Cis(Z)-flupentixol in maternal serum, amniotic fluid, umbilical cord serum, and milk.

A venous blood sample and an umbilical cord blood sample were obtained from five young women treated with the neuroleptic drug, cis(Z)-flupentixol decanoate in Viscoleo (intramuscularly) or flupentixol (orally) at the time of giving birth. In two cases amniotic fluid was also obtained, and from three of the mothers milk and simultaneous blood samples were obtained in the lactation period. Concentrations of the active drug, cis(Z)-flupentixol were measured in serum, amniotic fluid, and milk by radioimmunoassay. It was found that the concentration of the active drug in umbilical cord serum (fetal serum) was lower than that in serum from the mother--the ratio being about 0.24. Thus the amounts of drug reaching the fetus are low, but they cannot be considered unimportant. The concentrations found in milk were about 30% higher than the serum concentrations. However, the amounts of drug administered to the neonate with the milk are very low and, unless the neonate differs considerably from the adult as to sensitivity to or metabolism of this particular drug, they are of no importance.

Adult↗
PubMed1980

Relationship between plasma ratio of tryptophan to competing amino acids and the response to L-tryptophan treatment in endogenously depressed patients.

The ratio of the plasma of total tryptophan to those amino acids that compete with tryptophan during transport into the brain was determined in 60 control subjects and 87 patients suffering from endogenous depression, all females. The plasma ratio in the control subjects showed a significant negative correlation with age. There was no significant difference in the distribution of the biochemical data between the control subjects and the depressed patients. There was a significant higher proportion of bipolar depressed subjects compared to unipolar depressives and patients of uncertain polarity who showed a plasma ratio in the lower normal range. Thirty-two patients were subsequently treated with L-tryptophan. In the patients who showed a particularly low plasma ratio of tryptophan to competing amino acids a remission frequency of 80% was observed on day 14. The efficacy of L-tryptophan in the patients who showed a plasma ratio within the upper normal range was extremely poor. The results suggest that the ratio in the plasma of tryptophan to competing amino acids is a useful predictor of the course of treatment of depressed subjects with L-tryptophan.

Adult↗