Myosin heavy chain mRNA transform to faster isoforms in immobilized skeletal muscle: a quantitative PCR study

A quantitative polymerase chain reaction (PCR) method was used to measure the quantities of type I, IIa, IIx, and IIb myosin heavy chain (MHC) mRNA in total RNA preparations of the soleus, gastrocnemius, and plantaris muscles of normal and hindlimb-immobilized rats. Type IIx and even type IIb MHC mRNA were demonstrated at extremely low levels in normal soleus, 2.1 +/- 0.4 x 10(5) and 5.0 +/- 0.2 x 10(5) molecules of mRNA per microgram total RNA, respectively. Immobilization for 1 wk significantly altered the gene expression of MHC isoforms. In soleus, both type IIx and IIb MHC genes became significantly upregulated, 24-fold (P < 0.005) and 2.6-fold (P < 0.05), respectively. In gastrocnemius, the level of type IIa MHC mRNA decreased by 51% (P < 0.01) and the level of type IIx MHC mRNA increased by 140% (P < 0.05). In plantaris, the level of type IIa MHC mRNA decreased by 58% (P < 0.005). In conclusion, immobilization changed the MHC mRNA profile in three different types of skeletal muscle toward faster isoforms. The quantitative results permit reliable evaluation of changes in mRNA levels.

Blood ketone bodies in congestive heart failure

OBJECTIVES

The present study was designed to assess whether blood ketone bodies are elevated in congestive heart failure (CHF) and whether ketonemia is related to the hemodynamic and neurohumoral abnormalities of CHF.

BACKGROUND

In CHF, consumption of the body's fat stores may become abnormally high, contributing to the development of cardiac cachexia. Increased mobilization of free fatty acids could, in theory, augment ketogenesis, but whether patients with CHF are prone to ketosis remains unknown.

METHODS

Forty-five patients with chronic CHF (mean age [+/- SD] 57 +/- 13 years) and 14 control subjects free of CHF (mean age 53 +/- 13 years) underwent invasive and noninvasive cardiac studies and determination of blood ketone bodies (acetoacetate plus beta-hydroxybutyrate), circulating free fatty acids, glucose, lactate, insulin, glucagon, growth hormone, cortisol, norepinephrine, N-terminal proatrial natriuretic peptide, tumor necrosis factor-alpha and interleukin-6 after an overnight fast.

RESULTS

Patients with CHF had elevated blood ketone bodies (median 267 mumol/liter, range 44 to 952) compared with control subjects (median 150 mumol/liter, range 31 to 299, p < 0.05). In the total study group, blood ketone bodies were related to pulmonary artery wedge pressure (r5 = 0.45, p < 0.001), left ventricular ejection fraction (r3 = -0.37, p < 0.01), right atrial pressure (r3 = 0.36, p < 0.01) and circulating concentrations of free fatty acids (r5 = 0.52, p < 0.001), glucose (r5 = -0.39, p < 0.001), norepinephrine (r3 = 0.45, p < 0.001), growth hormone (r5 = 0.30, p < 0.05) and interleukin-6 (r3 = 0.27, p < 0.05). In multivariate analysis, left ventricular ejection fraction, serum free fatty acids and serum glucose were independent predictors of ketonemia.

CONCLUSIONS

Blood ketone bodies are elevated in CHF in proportion to the severity of cardiac dysfunction and neurohormonal activation. This may be at least partly attributable to increased free fatty acid mobilization in response to augmented neurohormonal stimulation. Additional studies are needed to identify the detailed mechanisms and clinical implications of CHF ketosis.

Circulating anti-Helicobacter pylori immunoglobulin A antibodies and low serum pepsinogen I level are associated with increased risk of gastric cancer

Helicobacter pylori infection has been suggested to be associated with an increased risk of gastric cancer, and low levels of serum pepsinogen I (PG I) have been linked to atrophic gastritis, which is a risk factor for gastric cancer. In Finland, 39,268 persons from 25 cohorts participated during 1968-1972 in a health examination survey and were followed for up to 13 years. A nested case-control study was performed on 84 stomach cancer patients identified from the Finnish Cancer Registry and 146 controls matched for age, sex, and municipality. Serum samples drawn at the baseline study were analyzed. An elevated level of serum anti-H. pylori immunoglobulin A (IgA) antibodies (a titer > or = 70) and a low serum PG I level ( < 49 micrograms/liter) were associated with an increased risk of gastric cancer. The odds ratios were 2.52 (95% confidence interval (CI) 1.14-5.57) for high IgA and 2.68 (95% CI 1.35-5.30) for low PG I. For high immunoglobulin G (IgG) ( > or = 700), the odds ratio was only 1.50 (95% CI 0.70-3.22). When both high IgA and low PG I were present, the odds ratio was 5.96 (95% CI 2.02-17.57). The association of H. pylori infection with cancer became stronger with longer follow-up times, whereas that of low PG I was strongest at shorter follow-up times. Our findings support the hypothesis that H. pylori infection is a prevalent and potentially preventable cause of gastric cancer. They stress the value of IgA antibody determinations and provide new evidence for a pathogenesis leading from prolonged infection through atrophic gastritis to gastric cancer.

The combined effect of alcohol and physical exercise on serum testosterone, luteinizing hormone, and cortisol in males

The combined effect of alcohol and physical exercise on the serum levels of testosterone, luteinizing hormone, and cortisol was studied in healthy male volunteers by performing an exhaustive ergometer exercise (1) followed by alcohol intoxication (induced by 1.5 g of alcohol/kg body weight), (2) during alcohol intoxication (induced by 0.8 g of alcohol/kg body weight), and (3) during hangover (13 hr after a dose of 1.5 g of alcohol/kg body weight). Physical stress immediately before alcohol administration prolonged the depressant effect of alcohol on testosterone secretion. This seemed to be mainly a consequence of direct inhibition at the testicular level, even though the role of luteinizing hormone as a contributory regulatory factor cannot be totally ruled out. Cortisol response to exercise was not modified by alcohol under any of the experimental conditions.

Skeletal muscle fiber distribution influences serum high-density lipoprotein cholesterol level

Earlier we have shown a significant positive association between muscle fiber distribution, i.e. percentage of slow-twitch (ST) fibers in the vastus lateralis muscle, and serum high-density lipoprotein cholesterol (HDL-C) level. This association may be due to the fact that ST fibers have a high capacity for oxidative energy metabolism and a high number of surrounding capillaries. These fibers have a high capacity to metabolize fatty acids liberated by lipoprotein lipase (LPL) from triglyceride-rich lipoproteins. This in turn elevates serum HDL-C levels. Thus, a high percentage of ST fibers (ST-%) may be one factor having a beneficial effect on serum HDL-C concentration. A high ST-% may also increase the likelihood that a person will become involved in an endurance type of physical activity, which further increases serum HDL-C concentration by increasing further LPL activity in the capillary bed of skeletal muscle. In this paper we present a hypothetical background of the role that ST fibers may have on serum lipid and lipoprotein profile.

Lacrimal plugs as a therapy for contact lens intolerance

We investigated whether canalicular occlusion with a lacrimal plug could increase objective and/or subjective comfort in contact lens (CL) wearers (n = 9) with both a history of lens intolerance and relative tear fluid deficiency. A modified Schirmer test (MST) was performed with the lids closed and under topical anaesthesia. Patients with values of < or = 10 mm/5 min were included. The plugs were inserted into the inferior canaliculus of the eye with the lower MST result; the contralateral eye served as a control. Conjunctival hyperaemia, Rose-Bengal and fluorescein scores, as well as subjective irritation, decreased significantly in plugged eyes at the 1 month follow-up visit but had returned to the pre-operative level at the 3 month visit. Tear fluid plasmin activity was elevated prior to plug insertion. Plasmin activity of the plugged eye was significantly lower at the 1 month visit but neither tear fluid flow (in the collection capillary) nor plasmin release showed any changes. The mean MST value improved significantly, whereas conjunctival chemosis and limbal hyperaemia showed no improvement at the 1 or 3 month follow-up visits after inferior punctual occlusion. Occlusion of the lower canaliculus with a lacrimal plug seems to induce a relatively short-lasting subjective and objective benefit for CL wearers. Plug escape or adaptive changes in lacrimal fluid secretion/elimination rate probably took place during the follow-up. The association of increased plasmin activity with tear deficiency might lead to enhanced tissue proteolysis, and thus contribute to CL-related ocular surface changes.

Myosin heavy-chain fragments and cardiac troponins in the serum in rhabdomyolysis. Diagnostic specificity of new biochemical markers

BACKGROUND

Myosin is the major structural protein in muscle. Antibodies to beta-type heavy meromyosin react with cardiac and slow-twitch skeletal muscle. Cardiac TnT and TnI were developed as tissue-specific indicators.

OBJECTIVES

To study myosin heavy-chain fragments as a delayed marker of previous rhabdomyolysis. To examine the cardiac specificity of cardiac troponin T (TnT) and cardiac troponin I (TnI) in patients with severe skeletal muscle damage.

DESIGN AND METHODS

Serum myosin heavy-chain fragments, TnT, and TnI were studied up to 12 days after diagnosis in relationship to the serum creatine kinase level in 20 patients with rhabdomyolysis. The mean peak serum creatine kinase activity was 91,300 U/L. Myosin heavy-chain fragments were measured by an immunoradiometric assay, TnT by a one-step immunoenzymometric assay, and TnI by an immunoenzymometric assay.

RESULTS

Values for serum myosin heavy-chain fragments were greater than the upper limit of normal in all patients. The peak value (70 times the upper normal limit, on average) was usually achieved 4 to 7 days after the diagnosis of rhabdomyolysis, and it was increased up to 12 days. The peak level of TnT was increased in 95% of the patients, and it correlated strongly with the peak activity of serum creatine kinase. The highest TnI value was above the detection limit of myocardial infarction in 30% of the patients. Half of these patients were the only patients with ischemic changes observed on an electrocardiogram performed on admission to the hospital.

CONCLUSIONS

The measurement of myosin heavy-chain fragments was useful in the diagnosis of previous rhabdomyolysis up to 12 days. The role of TnT was negligible as an indicator of cardiac muscle damage in patients with severe rhabdomyolysis. Cardiac TnI is a more tissue-specific marker for myocardial damage even with concurrent rhabdomyolysis.

Tear fluid plasmin activity after excimer laser photorefractive keratectomy

PURPOSE

Elevated tear fluid plasmin activity may correlate with delayed healing of corneal wounds. The present study was performed to establish the tear fluid plasmin activity after photorefractive keratoablation (PRK).

METHODS

Tear fluid aspirated with microcapillaries was subjected to a fluorometric plasmin assay using the 7-amido-4-trifluoromethylcoumarin derivate of the tripeptide H-D-Val-Leu-Lys as substrate.

RESULTS

Tear fluid flow, plasmin activity, and flow-corrected plasmin excretion rate in tears (plasmin flux) were determined preoperatively and 1, 2, and 7 days after PRK. The preoperative tear fluid flow was 6.55 microliters/min (median; range, 1.8 to 21.8 microliters/min), plasmin activity was 1.29 IU/l (median; range, 0.6 to 6.9 IU/l), and the excretion of plasmin in tears was 11.7 microIU/min (median; range, 1.6 to 41.5 microIU). A statistically significant decrease in tear fluid plasmin activity was found during the follow-up period on the first (0.6 IU/l; range, 0.6 to 1.7 IU/l, P < 0.01) and second (0.65 IU/l; range, 0.6 to 1.49 IU/l, P < 0.01) postoperative days. On the other hand, significant elevation of both tear fluid flow and plasmin flux values occurred during the first two postoperative days. The median plasmin flux values on days 1, 2, and 7 were 57.35 microIU/min (range, 16 to 540 microIU/min, P < 0.01), 40.0 microIU/min (range, 13.3 to 222.8 microIU/min, P < 0.01), and 10.2 microIU/min (range, 2.2 to 90.7 microIU/min, P > 0.05), respectively.

CONCLUSION

The marked elevation of tear fluid flow coincided with the persistence of an epithelial defect. However, because of the acceleration of tear fluid flow, proteolytic activity due to plasmin (IU/l) actually decreases. Consequently, the increased excretion of plasmin in tears (plasmin flux) does not lead to highly elevated plasmin activity, which could inhibit wound healing. It seems to be a natural healing response because all corneas were epithelialized normally by or on day 3.

Elevation of tear fluid plasmin activity of contact lens wearers studied with a rapid fluorometric assay

Tear fluid plasmin activities were measured by a fluorometric assay based on a lyophilized kit with the 7-amido-4-trifluoromethylcoumarin derivative of the tripeptidyl H-D-Val-Leu-Lys as substrate. The rapid, sensitive method can detect proteolytic activity in small volume tear fluid samples. Plasmin activity levels (IU/L) measured from the samples were corrected with tear fluid flows (microliters/min), yielding a parameter called plasmin flux (microIU/min). Correction is important when patients show tearing due to irritation. Tear fluid samples were collected from 32 asymptomatic contact lens (CL) wearers and 27 controls. Plasmin activity values (2.7 +/- 0.3 IU/L) of CL wearers were higher (p < 0.00006) than those of the controls (1.6-0.1). Mean plasmin flow was 12.6 +/- 1.5 microliters/min for CL wearers and higher for controls (6.8 +/- 0.5 microliters/min). The difference was not significant (p = 0.063). Plasmin flux values of CL wearers (30.0 +/- 4.1 microIU/min) were conspicuously higher than those of controls (10.2 +/- 0.7 microIU/min, p < 0.00006). We conclude that elevated tear fluid proteolytic activity may be related to pathological changes associated with CL wear.

A rapid fluorometric assay for tear fluid plasmin activity

A rapid (5- to 10-min), sensitive (detection limit 0.6 IU/L), and moderately specific fluorometric plasmin assay for small volume tear fluid samples was developed. Addition of albumin (up to 0.1% final concentration) to the assay buffer improved the sensitivity of the test so that plasmin activity in healthy controls could be detected. pH in the reaction buffer was 8.0, Michaelis-Menten constant for the substrate, H-D-Val-Leu-Lys.7-amido-4-methyl-coumarin (AMC), was 0.28 mM, and final substrate concentration in the reaction buffer was 1 mM. Intra- and interassay imprecisions were 1.6 and 4.4%, respectively at a plasmin level of 10 IU/L. Tear fluid flow was significantly higher in the patients than in the healthy controls, and this dilatory effect must be considered when using plasmin determination for diagnostic purposes. This effect was counteracted by correcting the plasmin activity values by tear fluid flow. Plasmin flux is plasmin activity (microIU) secreted in units of time (min). This parameter showed highly significant differences between the patients and controls. All patients with microbial keratitis, corrosive trauma, ocular trauma, herpetic infection, and other diseases showed highly significant elevation of plasmin flux compared with controls. The highest plasmin flux values (several hundredfold that of controls) were recorded in patients with severe corneal ulcers. Few patient samples showed some involvement of other proteases, which were not inhibited by aprotinin.

Metabolic consequences of sustained suppression of free fatty acids by acipimox in patients with NIDDM

To examine whether overnight suppression of free fatty acid levels reduces hepatic glucose production, 20 NIDDM patients were given a slow-release formulation of the antilipolytic agent acipimox, in a double-blind crossover manner at bedtime for 4 wk. During acipimox treatment, serum free fatty acid concentrations were suppressed between 2400 and 0600 by 64% (P < 0.001), but no reduction in hepatic glucose production was observed (2.16 +/- 0.16 vs. 2.23 +/- 0.16 mg.kg-1 x min-1, acipimox vs. placebo). In contrast, from 0800 to 2000 a sustained 50% rise occurred in serum free fatty acids (P < 0.001). As a consequence, the 24-h area under the free fatty acid curve was similar during both treatment periods. In the morning, the rise in free fatty acid concentration occurred despite identical serum acipimox concentrations as those measured at midnight, when free fatty acid levels were suppressed. Although energy expenditure was higher (P < 0.05) during periods of elevated free fatty acid levels, the sums of energy expenditure measured in the morning and in the evening were similar during the acipimox and placebo periods. To exclude that the free fatty acid rise was caused by administration of acipimox only once at bedtime, additional experiments were performed administering acipimox every 2 h for 4 days. Despite similar acipimox concentration on day 1 and day 4 of this frequent dosing regimen, the free fatty acid concentrations were significantly higher on day 4 compared with day 1 (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of muscle and liver to glucose-fatty acid cycle in humans

To examine the influence of elevated free fatty acid (FFA) levels on hepatic glucose production (HGP) and oxidative and nonoxidative pathways of glucose metabolism, 12 healthy subjects participated in two euglycemic insulin-clamp studies performed with and without infusion of Intralipid plus heparin. To elucidate the role of skeletal muscle in this putative interaction, we performed muscle biopsies for the measurement of activities of glycogen synthase (GS), pyruvate dehydrogenase (PDH), and carnitine palmitoyltransferase (CPT). Infusion of Intralipid plus heparin caused an increase in plasma FFA concentrations and rate of lipid oxidation (measured by indirect calorimetry) that was not inhibited by insulin. Suppression of HGP by insulin was impaired by elevated plasma FFA levels. Furthermore, the increase in plasma FFA was associated with a 20% reduction in total glucose metabolism (P < 0.01), which was completely accounted for by a reduction in the rate of glucose oxidation. Although the fractional activity of GS was increased by insulin, elevation of plasma FFA had no influence on this key enzyme of glycogen synthesis. In addition, the activities of PDH and CPT were uninfluenced by the elevation of FFA, suggesting that oxidative processes in skeletal muscle were not a major target for the operative glucose-fatty acid cycle under the current conditions. Taken together, the data indicate that the interaction between FFA and glucose metabolism also involves impaired suppression of HGP by insulin.

Progressive unilateral hypertrophic myopathy: a case study

A 12-year-old girl had progressive unilateral muscle hypertrophy limited to the sole, tibialis anterior, and biceps femoris muscles. The affected muscles showed complex repetitive discharges by electromyography, necrosis and variation of fiber size upon histopathological examination, and increased metabolic activity in biochemical studies. The findings suggest a myopathic origin, but the actual cause remains unknown.

Bone mineral density and abstention-induced changes in bone and mineral metabolism in noncirrhotic male alcoholics

BACKGROUND AND PURPOSE

Abuse of alcohol may derange bone metabolism and cause osteoporosis. Due to confounding factors associated with alcohol abuse, however, the effect of alcohol itself on bone loss remains obscure. The influence of alcohol intake on bone and mineral metabolism is rather well known, but how the metabolism normalizes during withdrawal has rarely been investigated. The aims of the present study were to evaluate the alcohol-induced changes of bone and mineral metabolism and their recovery during abstention, and to reassess any possible link between alcohol abuse and osteoporosis.

PATIENTS AND METHODS

We studied 27 non-cirrhotic male alcoholics hospitalized for 2 weeks for withdrawal. For comparison, three groups of control subjects were examined. Serum and urinary parameters of bone and mineral metabolism as well as intestinal absorption of calcium were determined at the beginning and end of the treatment period. Bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry at four axial sites (lumbar spine, femoral neck, Ward's triangle, trochanter).

RESULTS

On admission, bone formation in the alcoholics was reduced as reflected by decreased serum levels of osteocalcin (-28%; p < 0.05) and procollagen I carboxyterminal propeptide (-17%; p < 0.05). Both parameters normalized within 2 weeks of abstention (p < 0.0001 and p < 0.01, respectively). Urinary hydroxyproline, a parameter of bone resorption, was at the control level on admission and increased slightly during abstention (p < 0.05). Serum ionized calcium increased by 3% (p < 0.0001) during withdrawal. Concomitantly, serum free fatty acids (FFA) decreased by 38% (p < 0.001), and there existed an inverse correlation (r = -0.50, p < 0.05) between changes in ionized calcium and FFA. Serum levels of intact parathyroid hormone and vitamin D metabolites were similar in patients and controls throughout the whole observation period. Intestinal absorption of calcium measured by stable strontium was 37% higher in alcoholics than in controls (p < 0.001); it decreased to nearly normal toward the end of the treatment period. Mean axial BMD did not differ between patients and controls at any of the four measurement sites. However, BMD decreased parallel with duration of drinking history in the alcoholics at all axial sites (p < 0.05 to < 0.01, analysis of covariance with age and weight as covariates).

CONCLUSIONS

Decreased bone formation, which is uncoupled from ongoing bone resorption, recovers completely during 2 weeks of abstention. In the absence of confounding factors, the central BMD is normal in noncirrhotic male alcoholics, although the negative effect of alcohol on BMD is evident when duration of excessive drinking is taken into account.

Beta-adrenergic system in myotonic dystrophy

Myotonic dystrophy (DM) is considered an inherited membrane disorder, but the basic defect is unknown. We studied plasma catecholamines as well as lymphocyte and muscle beta-adrenergic receptor densities and functioning in 19 DM patients and 15 control subjects. Plasma adrenaline and noradrenaline concentrations were not significantly different between DM patients and controls. In isolated lymphocytes basal cAMP production was 157 +/- 26 pmol/mg protein/10 min in DM patients and 91 +/- 12 pmol/mg protein/10 min in controls (n.s.), whereas isoproterenol-stimulated cAMP production was significantly higher in DM patients (285 +/- 42 pmol/mg protein) compared with control subjects (168 +/- 21 pmol/mg protein, P less than 0.05). Lymphocyte beta-adrenoceptor densities were similar among DM patients (50 +/- 3 fmol/mg protein) and controls (47 +/- 5 fmol/mg protein). beta-Adrenoceptor densities were also similar in muscle biopsy specimens (12.9 +/- 1 in DM and 13.1 +/- fmol/mg protein in controls). The correlation between lymphocyte and skeletal muscle receptor densities was r = 0.35 in DM patients and r = 0.22 in controls. The results do not support the hypothesis of adrenergic dysfunction in DM despite its membrane involvement.

Fatigue and changes of ATP, creatine phosphate, and lactate during the 400-m sprint

Fatigue during the 400-m sprint was studied by measuring muscle ATP, creatine phosphate (CP), lactate (M-La), and blood lactate (B-La) in six male runners before and after four experimental sprints (100, 200, 300, and 400 m). During the first 100 m, muscle CP decreased from 15.8 +/- 1.7 to 8.3 +/- 0.3 mmol/kg while M-La increased to 3.6 +/- 0.4 mmol/kg. After 200 m the CP had decreased to 6.5 +/- 0.5 mmol/kg and M-La had increased to 8.3 +/- 1.1 mmol/kg. At the end of the 400 meters, ATP and CP concentrations had decreased by 27% and 89%, respectively, and M-La had increased to 17.3 +/- 0.9 mmol/kg. It was concluded that after 200 m the speed of running decreased, although CP was not depleted and lactate concentration was not at maximum level. Complete fatigue occurred when CP stores were depleted and B-La and M-La attained an individual maximum.