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Biomedical subjects

H Kuipers

Publications and source records attributed to H Kuipers.

105 records · Page 6Linked to original sources
PubMed1985

Influence of a prostaglandin-inhibiting drug on muscle soreness after eccentric work.

Since the time sequence of exercise-induced muscle soreness corresponds well with the time sequence of exercise-induced morphological changes in animal skeletal muscle, it has been suggested that muscle soreness is related to an inflammatory response. Prostaglandins are assumed to play a role in the inflammatory process. The influence of a cyclo-oxygenase-inhibiting drug (flurbiprofen) on the subjective symptoms of soreness and eventual structural changes was investigated in six male subjects. The subjects performed one concentric and two eccentric work bouts of 30 min at 80% of the individual maximal work load on the bicycle ergometer. Muscle biopsies taken before, immediately after, and 24 h after work were used to examine structural, ultrastructural changes as well as for assessment of glycogen content. Plasma levels of muscle enzymes and subjective soreness were determined at regular intervals. Eccentric work elicited muscle soreness in all subjects: however, the soreness was consistently less in the second eccentric trial. No significant enzyme release was noticed in any of the subjects, whereas ultrastructural changes were restricted to the mitochondria. No influence of flurbiprofen on subjective soreness was noticed. After both eccentric trials muscle glycogen was lower 24 h after work compared to the content immediately after work. The results suggest that eccentric exercise interferes with glycogen synthesis and that prostaglandins do not play a major role in exercise-induced muscle soreness.

Adult↗
PubMed1984

Acid-base balance during repeated bouts of exercise: influence of HCO3.

Ten men and one woman were studied before, during, and following five 1-min cycling bouts (100% VO2 max) 1 h after consuming either 0.2 g/kg B.W. of NaHCO3 or a placebo drink (NaCl). The fifth exercise bout was performed until exhaustion and the time recorded to judge the effects of the NaHCO3 drink on performance. Blood samples taken from a forearm vein revealed that the intake of NaHCO3 increased resting pH (7.34 to 7.41), HCO3 (27.5 to 31.0 mM), and base excess (1.1 to 4.6 mM). During and following the exercise, blood pH and HCO3 were always higher (P less than 0.05) in the NaHCO3 than placebo trial. Performance times during the fifth cycling bout averaged 113.5 (SE +/- 12.4) and 160.8 (SE +/- 19.1) s in the NaCl and NaHCO3 trials, respectively. This 42% difference between the means was significant at the 0.01 level. The blood hydrogen ion to lactic acid ratios (nM/mM) measured between each exercise bout and during recovery from the exhaustive fifth bout suggests that the enhanced performance during the NaHCO3 trial was the result of greater buffer capacity. Thigh muscle (vastus lateralis) pH measured immediately before the fifth cycling bout in four of the subjects revealed that the working muscles were less acid in the NaHCO3 trial (pH = 6.81) than during the NaCl treatment (pH = 6.73). Thus, the alkalizing influence of oral HCO3 supports the concept that the hydrogen ion concentration in blood and muscle has a direct influence on performance during repeated, supramaximal exercise.

Acid-Base Equilibrium↗
PubMed1984

Infection with cytomegalovirus in homosexual men.

The prevalence and incidence of cytomegalovirus (CMV) infections were studied in a group of homosexual men. Of the 710 participants, 501 (70.6%) had complement fixing antibodies to CMV on entry to the study. During the follow up (maximum 23 months) 69 CMV infections were found: 50 primary infections among the 209 seronegative men (attack rate 27.3%), and 19 recurrent infections among the 501 seropositive men (attack rate 6.2%). The prevalence of antibody to CMV was correlated with four characteristics of the participants' lifestyles: duration of homosexual activity, number of different sexual partners, history of syphilis, and anal sexual contact. Among the seronegative men, the incidence of primary infection with CMV correlated with a history of syphilis and anal sexual contact. We conclude that infections with CMV are highly prevalent among homosexual men, and that anal sexual contact plays an important part in the transmission of this virus.

Adult↗
PubMed1983

Prevalence and incidence of hepatitis A among male homosexuals.

In a study of 689 male homosexuals 290 (42%) were found to have antibodies to hepatitis A virus. The 399 men who did not have antibodies were followed up for up to 690 days, and 35 cases of hepatitis A were detected. The attack rate at the end of the study was 14%. The incidence climbed steadily, indicating that the cases of hepatitis A did not occur in clusters. Statistical analysis showed that the prevalence of antibodies to hepatitis A virus was significantly correlated with the duration of homosexual activity (p less than 0.006), and this was independent of age. The incidence of hepatitis A was found to be correlated with the number of different sexual partners in the preceding six months. It is concluded that hepatitis A is a sexually transmitted disease among homosexual men in countries with a low rate of exposure to hepatitis A during childhood.

Adolescent↗
PubMed1983

Muscle degeneration after exercise in rats.

To search for morphological changes in muscle, related to overuse syndromes of muscle due to exercise, groups of untrained rats ran on a treadmill for 1 h at submaximal intensity. Each group was sacrificed at a different interval after the end of the exercise. To evaluate the physiologic load, the colonic temperature and blood lactate level were determined. The right hindlimb was fixated with buffered glutaraldehyde, injected into the femoral artery, and different muscles were dissected and prepared for electron and light microscopy. The muscles of the left limb were frozen in liquid Freon and used for histochemistry. Signs of degeneration were noted in the soleus, rectus femoris, and vastus lateralis muscles, but were absent in the gastrocnemius, tibialis anterior, extensor digitorum, and biceps femoris muscles. Immediately after exercise, only minor signs of degeneration were observed at the ultrastructural level, while after 2-3 h degeneration became clearly visible at the light microscopic level. The most pronounced changes were observed 24-48 h after exercise, whereafter regeneration occurred. Only 2%-5% of all fibers in the soleus muscle showed signs of degeneration, while in the vastus lateralis and rectus femoralis muscle less than 0.5% of the fibers were affected. The affected fibers showed degeneration only in segments with a length between 150-1250 micrometers. The affected fibers in the soleus and vastus lateralis muscles belong to the type I population, while in the rectus femoris type I as well as type II fibers were affected.

Animals↗
PubMed1983

Efficacy trial of heat-inactivated hepatitis B vaccine (CLB) in male homosexuals in the Netherlands.

The efficacy of a heat-inactivated hepatitis B virus (HBV) vaccine, containing 3 micrograms-HBsAg, was studied among a group of 800 susceptible homosexual men. The trial was conducted randomized, placebo-controlled and double blind. At the trial end point (21.5 months) the attack-rate for all HBV infections together was 4.8% among vaccinees and 23.8% among the placebos (p less than 0.0001). Four months after the first injection 89% of the vaccinees had formed anti-HBs and this percentage declined only slightly during the follow-up period. Maximum titers were reached 5 months after the first vaccination. None of the vaccinees who responded to the vaccine with anti-HBs greater than or equal to 1 mIU/ml developed a HBsAg positive infection. The vaccine had no serious side-effects.

Clinical Trials as Topic↗
PubMed1982

Limitations of concentration measurements for evaluation of endocrine status of exercising women.

The impact of changes in metabolic clearance rates (MCR), biologic activity of sex-steroids, steroid-protein interaction and steroid-binding properties of plasma proteins in relation to physical exercise are reviewed. The MCR of estradiol is decreased during physical exercise but this phenomenon is only partly explained by a decreased hepatic blood flow. Changes in concentration of high-affinity steroid binding proteins (testosterone-estradiol-binding globulin, TeBG) affect predominantly the amount of free testosterone (T) and its MCR. During exercise both the lower sex-steroids binding affinities of plasma proteins due to increased body temperature and the increased concentration of these hormones cause a shift towards an increased free concentration. Due to competitive interactions between androgens and estrogens for the binding site of TeBG the free concentration of estrogens will probably increase more than expected. The physiological meaning of these changes are discussed.

Adolescent↗
PubMedDate not supplied

Physiological, biochemical and psychological markers of strenuous training-induced fatigue.

The purpose of the study was to investigate whether severe fatigue, possibly leading to overreaching, could be diagnosed at an early stage by a combination of parameters. Seven well-trained male subjects (age [mean +/- SD]: 25.3 +/- 4.7 yr; body mass: 76 +/- 6.6 kg; VO2max: 61.1 +/- 7 ml.kg(-1).min(-1)) increased their training load by doubling their training volume and increasing the intensity by 15 % over a period of two weeks. Before and after this intensified training period subjects underwent a series of tests including a maximal incremental cycle ergometer test (Wmax) with continuous ventilatory measurements and blood lactate values, time trial, basal blood parameter tests (red and white blood profile), hormones [growth hormone (GH), insulin-like growth factor 1(IGF-1), adreno-corticotropic hormone (ACTH), cortisol], neuro-endocrine stress test [short insulin tolerance test (SITT), combined anterior pituitary test (CAPT) and exercise], a shortened Profile of Mood State (POMS), the estimated rate of perceived exertion (RPE) and a cognitive reaction time test. The intensified training period resulted in a significant increase of the training load (p <0.01), training monotony (p <0.01) and training strain (p <0.01). The RPE during training increased significantly (p <0.01) during the intensified training period. Total mood score obtained from the POMS tended to increase (p=0.06), reflecting an increase in worse mood state. A novel finding was that reaction times increased significantly, indicating that overreaching might adversely affect speed of information processing by the brain, especially for the most difficult conditions. After the intensified training period, neither changes in exercise-induced plasma hormone values, nor SITT values were observed. During the CAPT only cortisol showed a significant decrease after the intensified training period. Hemoglobin showed a significant decrease after the intensified training period whereas hematocrit, red blood cell count (RBC) and MCV tended to decrease. The intensified training had no effect on physical performance (Wmax or time trial), maximal blood lactate, maximal heart rate and white blood cell profile. The most sensitive parameters for detecting overreaching are reaction time performance (indicative for cognitive brain functioning), RPE and to a lesser extend the shortened POMS. This strongly suggests, that central fatigue precedes peripheral fatigue. All other systems,including the neuro-endocrine, are more robust and react most likely at a later stage in exhaustive training periods.

Adult↗
PubMedDate not supplied

Hemoglobin and hematocrit values after saline infusion and tourniquet.

This study attempted to contribute to standardization of blood testing in sport, and to investigate the effect of artificial dilution with saline. In 10 healthy, physically active males and 3 healthy physically active females hemoglobin (Hb), hematocrit (Ht), and % reticulocytes (%retics) were measured at different time points to look for possible fluctuations during day time, while the subjects had regular coffee breaks and lunch. In 7 of the subjects in a separate experiment 500 ml of saline were infused around 8 am and Hb, Ht, and %retics were measured before and every hour thereafter until 7 hours after infusion. In addition Ht was measured on a hematological analyzer as well as with a centrifuge. In a separate experiment the effect of tourniquet duration on Hb and Ht was studied in 9 of the subjects. The results show that Hb, Ht, and %retics are stable from 8 am to 4 pm, but that infusion of 500 ml of saline induces an acute decrease in Hb and Ht within one hour (Hb decreased from 15.2+/-0.9 g/dl to 14.5+/-1.0 g/dl, and Ht from 45.6+/-2.8 % to 44.0+/-2.5 %). The decline in Hb and Ht was maintained during the 7-hour observation period. Ht values of the same samples measured with a hematological analyzer and a centrifuge were not different. Application of the tourniquet did significantly affect Hb and Ht values only from two minutes, and thereafter Hb and Ht remained stable during the rest of the 5-minute tourniquet. With blood testing in sport these results have to be taken into consideration.

Adult↗
PubMedDate not supplied

Influence of therapeutic doses of amoxicillin on aerobic work capacity and some strength characteristics.

The purpose of this study was to investigate whether or not amoxicillin in therapeutic doses could have an influence on maximal aerobic work capacity and some strength characteristics in trained subjects. Fifteen volunteers (men; age range, 21 to 38 years; mean, 28.8 years) were examined once weekly for 4 consecutive weeks, and on these occasions the following variables and parameters were measured: maximum workload attained on the bicycle ergometer, maximum heart rate, maximum serum lactate concentration, heart rate and serum lactate concentration after 10 min at 80% of the maximum workload attained, maximum isometric extension force of the legs, vertical jump height, and body weight. During the baseline period, the determined variables and parameters did not show any significant difference between Test 1 and Test 2. During the 3rd and 4th week of the test period, the subjects received at random either placebo (6-aminopenicillanic acid) or amoxicillin in therapeutic doses (375 mg, 3 times a day) every day for 5 days. After the third test in the 3rd week, there was a cross-over, ensuring that each volunteer was examined during placebo as well as during amoxicillin medication. The serum amoxicillin levels were determined. After statistical analysis, no influence of amoxicillin or placebo on the parameters and physiologic variables was demonstrable.

Adult↗