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Biomedical subjects

H Lithell

Publications and source records attributed to H Lithell.

At least 253 records · Page 14Linked to original sources
PubMed1983

Ovarian function, bleeding control and serum lipoproteins in women using contraceptive vaginal rings releasing five different progestins.

Ovarian function, bleeding patterns and serum lipoproteins were studied in women using contraceptive vaginal rings (CVRs) of dimethyl-polysiloxane impregnated with steroids. The different CVRs were used for about 10 cycles each. The following groups were studied, with the daily steroid dosage given in parentheses. Women using CVRs delivering levonorgestrel (290 micrograms), norethisterone (850 micrograms), medroxyprogesterone acetate (700 micrograms) or megestrol acetate (1.9 mg), all of which were in combination with estradiol (200 ug). Women using CVRs delivering progesterone (5.2 mg). Women taking megestrol acetate orally (15 mg/day) for three weeks. In all women except those using the levonorgestrel CVR, there were indications of incomplete suppression of ovarian activity as shown by elevated levels of progesterone and/or estradiol peaks. Bleeding control seemed to be good with the levonorgestrel CVR and rather poor with the others. Levonorgestrel treatment was associated with a decrease in high density lipoprotein cholesterol (32%) and triglycerides (25%) and a 16% decrease in apolipoprotein A-I. Norethisterone induced a 10% decrease in A-I and a reduction of cholesterol in very low density lipoprotein. All other lipid and apolipoprotein B, A-I and A-II values were unaltered with the administration of the CVRs and with oral megestrol acetate. Levonorgestrel was given in a higher dose than the other progestins, but the absence of effects of the high oral dose of megestrol acetate on the serum lipoproteins indicates that the progesterone-derived progestins in adequate doses probably would not alter the lipoprotein metabolism. Higher doses of progestins are needed to achieve acceptable control of ovarian activity and bleeding patterns than seen with these CVRs.

Cholesterol↗
PubMed1983

Increase in skeletal muscle lipoprotein lipase following endurance training in man.

The effect of regular physical training on skeletal muscle lipoprotein lipase activity (LPLA) was investigated in 16 healthy men of normal body weight. They trained on cycle ergometers for 8 weeks. During the training period half the group were given the beta-adrenergic receptor blocker propanolol (160 mg/day) and the other half placebo tablets. Muscle tissue samples were taken before the training period and 4 days after the last training session and drug intake to ensure that there were no acute effects of either training or drug treatment. The maximal oxygen uptake (Vo2max, 1/min) increased by 8% with training. LPLA increased by 47% and 31% in the placebo and beta-blockade group, respectively. Capillary density increased by 19% and 17%. The statistical analysis revealed a significant effect of training but not of beta-blockade on these changes. The present longitudinal training study in healthy men confirms the results of cross-sectional studies showing higher muscle LPLA in well-trained than in sedentary men.

Adult↗
PubMed1983

The influence of a high dietary intake of purine-rich animal protein on urinary urate excretion and supersaturation in renal stone disease.

1. Eight recurrent renal stone-forming patients were housed in a metabolic ward and fed on a low (LPD) and a high (HPD) animal protein diet, which were isoenergetic. Metabolic studies were made after 2 weeks on each diet. 2. There was a 90% increase in urinary urate on HPD compared with LPD, whereas serum urate did not change consistently. 3. The urinary acid excretion increased by 200%, including a 100% increase in ammonium ion excretion. A fall in urine pH by 0.9 unit was also seen. 4. The calculated ion activities of the urines revealed a profound increase in the uric acid supersaturation, from undersaturation to supersaturation, and in some cases even surpassing the formation product ratio. The ammonium urate supersaturation also increased. The sodium urate supersaturation was unchanged, despite an induced natriuresis. 5. The risk of forming uric acid or ammonium urate crystals or stones in the urine was increased on a high protein diet, whereas the risk of forming sodium urate crystals was no greater than on a low protein diet. 6. As uric acid and ammonium urate crystals under certain conditions may adsorb a macromolecular fraction of the human urine, which inhibits calcium oxalate crystal growth, it is proposed that this mechanism, along with a decrease in urine pH, may also interfere with the inhibitory activity of calcium oxalate crystal growth and aggregation.

Adult↗
PubMed1983

Similar serum lipoprotein reductions by lipid-lowering diets with different polyunsaturated:saturated fat values.

Lipid-lowering diets enriched in polyunsaturated fat decrease the serum cholesterol in hyperlipoproteinaemia, usually by reducing both the low-density-lipoprotein (LDL) and high-density-lipoprotein (HDL) cholesterol concentrations. The aim of the present study was to investigate whether the effects on LDL could be maintained but those on HDL cholesterol be diminished by reducing the ratio, polyunsaturated:saturated fat (P:S) of the diet. Twenty hyperlipoproteinaemic patients (six with type IIa, eight with type IIb and six with type IV) in a metabolic ward were given two fat-modified diets during two consecutive 3-week periods in a randomized order. The diets were identical with regard to nutrient composition but differed with regard to the P:S values, which were 2.0 and 1.3 respectively. The lipoprotein-lipid composition and serum apolipoprotein concentrations were similar at the end of the two dietary periods in type IIa and type IV patients but in type IIb patients a more pronounced reduction of the LDL-cholesterol concentration by 9% (P less than 0.05) was achieved on the diet with the higher P:S value. The HDL-cholesterol did not differ significantly. The results indicate that increasing the P:S value of lipid-lowering diets from 1.3 to 2.0 does not offer a great advantage with regard to the lipoprotein-lipid reductions achieved in moderate hyperlipoproteinaemia.

Adult↗
PubMed1983

Effects of continuous levonorgestrel treatment (subcutaneous capsules) on the lipoprotein and carbohydrate metabolism in fertile women.

The lipoprotein and carbohydrate metabolism was studied during contraceptive treatment with levonorgestrel, released at a low rate (70 micrograms/day) from subcutaneous capsules, in five women who were treated for 180-403 days. The serum cholesterol concentration decreased slightly but significantly during treatment. This was attributable to a tendency to a reduction of cholesterol in high-density lipoproteins. The treatment did not affect the lipoprotein lipase activity in adipose tissue. The elimination rates of intravenously injected fat and glucose were unchanged, as were the serum insulin concentrations. Thus, in this pilot study the concentration and composition of the serum lipoproteins altered to only a minor extent during treatment with levonorgestrel in a dose of 70 micrograms/day.

Adult↗
PubMed1983

Changes in metabolism during a fasting period and a subsequent vegetarian diet with particular reference to glucose metabolism.

During an investigation on the effect of fasting and a vegetarian diet on the symptoms and signs in chronic cutaneous and arthritic diseases studies were made of glucose metabolism, liver function and the plasma concentration and urine excretion of some minerals. The study was performed on 27 patients who stayed as in-patients on a metabolic ward for five weeks. After the fasting period the blood glucose and serum insulin concentrations were lower (p less than 0.01) than before the fast. At the end of the period on the vegetarian (vegan) diet (three weeks) the insulin/glucose ratio was lower than at the start of the fast. Serum enzyme concentrations reflecting liver function increased during the fast, but normalized during the vegan diet. The intake of vitamin B12 and of selenium due to the vegan diets was very low, which may give reason for some concern during long-term use of this type of vegetarian diet.

Adult↗
PubMed1983

A fasting and vegetarian diet treatment trial on chronic inflammatory disorders.

Twenty patients with arthritis and various skin diseases were studied on a metabolic ward during a 2-week period of modified fast followed by a 3-week period of vegetarian diet. During fasting, arthralgia was less intense in many subjects. In some types of skin diseases (pustulosis palmaris et plantaris and atopic eczema) an improvement could be demonstrated during the fast. During the vegan diet, both signs and symptoms returned in most patients, with the exception of some patients with psoriasis who experienced an improvement. The concentrations of lactoferrin in serum reflect the turnover and activity of neutrophil leukocytes. When this protein was initially increased it fell to normal values in most cases. The improvement or impairment of signs and symptoms was related to the lactoferrin levels in serum.

Adult↗
PubMed1983

The relationship between the basal lipolytic and lipoprotein lipase activities in human adipose tissue.

The basal rate of lipolysis and basal lipoprotein lipase activity were determined in vitro in subcutaneous adipose tissue obtained from eight healthy non-obese subjects, ten obese subjects before and during one week's starvation, nine untreated non-insulin dependent diabetics and seven treated non-insulin dependent diabetics whose disease had been under metabolic control for at least three months. There was a negative correlation between the rate of lipolysis and activity of lipoprotein lipase in untreated diabetes mellitus and during starvation (r from -0.87 to -0.81). Under these two conditions the rate of lipolysis is increased and the lipoprotein lipase activity is decreased. There was no correlation between lipolysis and lipoprotein lipase in non-obese subjects, non-starving obese subjects and treated diabetic patients (r from 0.11 to 0.36). Thus, during starvation and in untreated diabetes, there is a strong reciprocal relationship between basal lipolytic activity and basal lipoprotein lipase activity in human adipose tissue which is not found under normal conditions or in obesity and well-controlled diabetes. It is concluded that a negative connection between lipolysis and lipoprotein lipase in human adipose tissue may be of physiological importance for the regulation of the energy balance in conditions such as untreated non-insulin dependent diabetes and starvation where adipose tissue lipids are the major source of energy.

Adipose Tissue↗
PubMed1983

Muscle glycogen in soldiers on different diets during military field manoeuvres.

Severe skeletal muscle glycogen depletion has been previously reported for soldiers participating in field exercises. The purpose of the present study was to determine if the distribution of amplified food rations would reduce the extent of glycogen depletion during military field manoeuvres. Needle biopsy samples were obtained from the m. vastus lateralis of soldiers both before and immediately after their participation in 4.5 d of field exercises. Eight soldiers received normal rations while a second group of eight soldiers received rations which were amplified in both caloric value and the proportion of carbohydrates. Intramuscular glycogen concentrations before and after the manoeuvres averaged 120 and 55 mmol glucose units . kg-1, respectively. The group which received amplified rations did not exhibit glycogen levels significantly different from those using normal rations.

Adult↗
PubMed1983

Dietary animal protein and urinary supersaturation in renal stone disease.

Eight stone-forming patients were given diets that were high (HPD) and low (LPD) in dietary animal protein, each for two weeks. Urines were collected by the end of each diet period. Urinary calcium, phosphate, urate and acids were increased on HPD whereas citrate and urine-pH decreased. The urinary supersaturation and thereby the risk of forming crystals and stones of uric acid and ammonium urate was increased on HPD. The supersaturation of calcium oxalate was unchanged, but the inhibition of calcium oxalate crystallisation may have become unfavourably affected.

Calcium↗
PubMed1982

Changes in glucose tolerance and plasma insulin during lipid-lowering treatment with diet, clofibrate and niceritrol.

In an effort to reduce serum lipids in patients with atherosclerotic manifestations, a combined treatment with a conventional lipid-lowering diet, clofibrate and niceritrol was used. The effect on glucose metabolism of such treatment was studied. Among the 106 patients 66 took the full dose of both drugs and of these 51 were weight-stable and non-diabetic. The effects of the diet and the drugs were evaluated in this subsample. Diet had no effect on fasting blood glucose concentration, the K value of an intravenous glucose tolerance test (IVGTT) and concentrations of serum insulin. Niceritrol treatment was associated with increased blood glucose, decreased K value, elevated fasting serum insulin and serum insulin at 60 min during IVGTT. Clofibrate had the opposite effects to niceritrol and when both drugs were combined, carbohydrate metabolism was unchanged compared with the pre-treatment state.

Aged↗
PubMed1982

Diverging effects of cholestyramine on apolipoprotein B and lipoprotein Lp(a). A dose-response study of the effects of cholestyramine in hypercholesterolaemia.

Nineteen hypercholesterolaemic patients were randomly treated with either 16 or 8 g cholestyramine with a changeover after 6 weeks for a second 6-week period. During a third consecutive 6-week period all patients received 4 g cholestyramine daily. The low density lipoprotein (LDL) cholesterol and triglyceride concentrations decreased significantly (- 11%, - 21% and - 26% for LDL cholesterol on 4, 8 and 16 g, respectively) with a dose-response effect. However, the increase from 8 g to 16 g only caused a modest additional reduction of the lipid levels. The serum concentration of apolipoprotein (apo) B was correlated to the LDL cholesterol and decreased similarly in a dose-response fashion. However, the average reduction of apo B was less pronounced (- 4%, - 13% and - 17% on 4, 8 and 16 g of cholestyramine, respectively) resulting in a significant change of the apo B/LDL cholesterol ratio during treatment. There was a significant increase of the high density lipoprotein (HDL) cholesterol concentration, which was similar at all dose levels. Also, the apo A-I concentration in serum increased significantly but the relative decrease was less pronounced than that of HDL cholesterol, causing a significant decrease of the apo A-I/HDL cholesterol ratio. The apo A-II concentration in serum was unchanged or slightly decreased and the apo A-I/apo A-II ratio increased significantly.

Adolescent↗
PubMed1982

Elevated lipoprotein lipase activity in skeletal muscle tissue during treatment of hypertriglyceridaemic patients with bezafibrate.

Eleven hypertriglyceridaemic patients were treated with 600 mg bezafibrate daily for 2 months. The mean serum triglyceride concentration decreased by 35% (P less than 0.01) corresponding to a reduction in the very low density lipoprotein triglycerides by 41% (P less than 0.01). The high density lipoprotein cholesterol concentration and the serum concentration of apolipoproteins AI and AII increased by 19% (P less than 0.02), 11% (N.S., P less than 0.08) and 24% (P less than 0.01), respectively. The fractional removal rate (K2) in the intravenous fat tolerance test (IVFTT) increased by 37% (P less than 0.001). This was associated with significant increase of the skeletal muscle lipoprotein lipase activity ( + 39%, P less than 0.05). The mean value for the adipose tissue lipoprotein lipase activity remained unchanged. The K2 at IVFTT was correlated highly significantly to the activity of skeletal muscle lipoprotein lipase (r = 0.85, P less than 0.01). The present study indicates that the main reason for the reduction of the serum triglycerides during treatment with bezafibrate may be an increased activity of the skeletal muscle tissue lipoprotein lipase activity.

Adipose Tissue↗
PubMed1982

Decrease of lipoprotein lipase activity in skeletal muscle in man during a short-term carbohydrate-rich dietary regime. With special reference to HDL-cholesterol, apolipoprotein and insulin concentrations.

Seven men took part in a study in which the diet was changed from an ordinary mixed one to a fat-rich diet [greater than 70% energy (E)] for 3 days followed by a carbohydrate-rich diet (greater than 70% E) for 3 days. Blood was drawn and muscle biopsies [for analysis of lipoprotein-lipase (LPL) activity] were taken before the study and at the end of each diet period. Insulin, apolipoprotein (apo) B, A-I and A-II, cholesterol and triglyceride concentrations were determined in serum and the lipids also in the high density lipoproteins (HDL). Serum insulin was higher (p less than 0.01) during the carbohydrate-rich diet than during the fat-rich diet (12.0 +/- 0.9 vs. 7.5 +/- 0.5 microunits/l, mean +/- SEM), as were serum-triglycerides (2.42 +/- 0.27 vs. 0.98 +/- 0.07 mmole/1, p less than 0.001). Muscle LPL activity, on the other hand, was lower (p less than 0.01), 27.3 +/- 6.1 vs. 75.1 +/- 13.2 microunits/g. HDL-cholesterol was 1.22 +/- 0.08 during the carbohydrate-rich diet which was lower (p less than 0.01) than during the fat-rich diet, 1.45 +/- 0.11. The concentration of apo A-I and A-II did not vary significantly. It is suggested that the increased insulin concentrations during a short-term, carbohydrate-rich diet may have a down-regulating effect on muscle LPL activity. Low muscle LPL activity may account for part of the elevation of serum triglycerides. An ineffective hydrolysis of VLDL-triglycerides may contribute to the variation in HDL-cholesterol concentration seen under these circumstances.

Adolescent↗
PubMed1982

Short-term influence of a post-synaptic alpha-adrenoceptor blocking drug (prazosin) on carbohydrate metabolism.

Since sympathetic nervous activity is intimately involved in the regulation of hormonal and metabolic responses, it may be assumed tht antihypertensive drugs acting on adrenergic receptors will interfere with metabolic control mechanisms. We have therefore evaluated the effect of the selective alpha 1-adrenoceptor blocker prazosin on intravenous glucose tolerance and insulin response in a group of 6 healthy subjects. Ninety minutes after a single oral dose of 2 mg prazosin we observed a significant (p less than 0.05) fall in K-value (mean decrease from 1.7 to 1.0), which was accompanied by a blunting of the early insulin response. The acute effects of prazosin closely resemble those observed after 6-8 weeks of treatment with therapeutic doses of prazosin in hypertensive women. It is postulated that the effect of prazosin is mediated by an increase in circulating catecholamines acting on the pancreatic beta-cell alpha 2-adrenoceptors, which are responsible for the well-known inhibitory action of alpha-adrenergic agents upon the release of insulin.

Adrenergic alpha-Antagonists↗
PubMed1982

Coupling between dietary changes, reduced body weight, muscle fibre size and improved glucose tolerance in middle-aged men with impaired glucose tolerance.

Fourteen middle-aged med with impaired glucose tolerance were studied prior to and 6 months after exchange of simple carbohydrates for complex carbohydrates rich in fibers and saturated for polyunsaturated fats in their diet when exchangeable. Body weight was reduced by 6.4 kg (p less than 0.001). Physical work capacity was unchanged. Fasting blood glucose and insulin were lowered (p less than 0.001) at 6 months and so were the values during an OGTT at 120 min. Both serum triglyceride and cholesterol concentrations were reduced (p less than 0.01) by the changes diet, the most marked reduction being found in the VLDL fraction. HDL levels increased by 21% (p less than 0.01). Enzyme activities in gastrocnemius muscle specimens were subnormal and uninfluenced by changed dietary habits. The number of capillaries per fiber was normal throughout, but as muscle fiber size was reduced in relation to the decreased body weight, the number of capillaries/mm2 increased during the dieting period. It is suggested that the observed improvement in insulin sensitivity and glucose tolerance after a dietary period with weight reduction is related to and partly explained by shorter diffusing distances in weight-bearing muscles.

Age Factors↗
PubMed1982

Dietary effects on glycogen and lipoprotein lipase activity in skeletal muscle in man.

The influence of short-term adaptation to a fat and protein enriched diet (F + P) and a carbohydrate enriched diet (CHO) on skeletal muscle lipoprotein lipase (LPL) activity and muscle glycogen levels was evaluated in 7 males. Muscle biopsies were taken from the m. vastus lateralis after an uncontrolled, mixed diet (M), after a 3 day F + P) diet preceded by intense exercise, and after a 3 day CHO diet. After the F + P diet glycogen concentration was 55% that of the M diet while LPL activity increased by 21% (n.s.). After the CHO diet glycogen levels increased by 82% and LPL activity decreased by 55% compared to the M diet (p less than 0.01). The changes in LPL after the CHO diet were related to the changes in glycogen concentration (r = 0.98, p less than 0.01). LPL activity in the control situation was directly related to percent slow twitch (ST) muscle fibre type (r = 0.95, p less than 0.01). The results suggest that the uptake of fat from the circulation may be actively regulated by the muscle as a function of intramuscular substrate availability and that this regulation may be related to muscle fibre type composition.

Adolescent↗