Prevention of organ allograft rejection by a specific Janus kinase 3 inhibitor

Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.

Effects of aging, sex, and physical training on cardiovascular responses to exercise

BACKGROUND

The relative contributions of decreases in maximal heart rate, stroke volume, and oxygen extraction and of changes in body weight and composition to the age-related decline in maximal oxygen uptake (VO2max) are unclear and may be influenced by sex and level of physical activity.

METHODS AND RESULTS

To investigate mechanisms by which aging, sex, and physical activity influence VO2max, we quantified VO2, cardiac output, and heart rate during submaximal and maximal treadmill exercise and assessed weight and fat-free mass in healthy younger and older sedentary and endurance exercise-trained men and women. For results expressed in milliliters per kilogram per minute, a three-to-four-decade greater age was associated with a 40-41% lower VO2max in sedentary subjects and a 25-32% lower VO2max in trained individuals (p less than 0.001). A smaller stroke volume accounted for nearly 50% of these age-related differences, and the remainder was explained by a lower maximal heart rate and reduced oxygen extraction (all p less than 0.001). Age-related effects on maximal heart rate and oxygen extraction were attenuated in trained subjects (p less than 0.05). After normalization of VO2max and maximal cardiac output to fat-free mass, age- and training-related differences were reduced by 24-47% but remained significant (p less than 0.05). For trained but not sedentary subjects, maximal cardiac output and stroke volume normalized to fat-free mass were greater in men than in women (p less than 0.05).

CONCLUSIONS

A lower stroke volume, heart rate, and arteriovenous oxygen difference at maximal exercise all contribute to the age-related decline in VO2max. Effects of age and training on VO2max, maximal cardiac output, and stroke volume cannot be fully explained by differences in body composition. In sedentary subjects, however, the sex difference in maximal cardiac output and stroke volume can be accounted for by the greater percentage of body fat in women than in men.

Muscle triglyceride utilization during exercise: effect of training

The respiratory exchange ratio (RER) is lower during exercise of the same intensity in the trained compared with the untrained state, even though plasma free fatty acids (FFA) and glycerol levels are lower, suggesting reduced availability of plasma FFA. In this context, we evaluated the possibility that lipolysis of muscle triglycerides might be higher in the trained state. Nine adult male subjects performed a prolonged bout of exercise of the same absolute intensity before and after adapting to a strenuous 12-wk program of endurance exercise. The exercise test required 64% of maximum O2 uptake before training. Plasma FFA and glycerol concentrations and RER during the exercise test were lower in the trained than in the untrained state. The proportion of the caloric expenditure derived from fat, calculated from the RER, during the exercise test increased from 35% before training to 57% after training. Muscle glycogen utilization was 41% lower, whereas the decrease in quadriceps muscle triglyceride concentration was roughly twice as great (12.7 +/- 5.5 vs. 26.1 +/- 9.3 mmol/kg dry wt, P less than 0.001) in the trained state. These results suggest that the greater utilization of FFA in the trained state is fueled by increased lipolysis of muscle triglyceride.

Effects of gender, age, and fitness level on response of VO2max to training in 60-71 yr olds

The adaptive response of maximal aerobic power (VO2max) to endurance exercise training was compared in 53 men and 57 women, aged 60-71 yr. The subjects were healthy and had been sedentary for at least 2 yr. Pretraining VO2max was measured during graded treadmill walking on two occasions. These values were reproducible (24.4 +/- 4.7 vs. 24.4 +/- 4.6 (SD) ml.min-l.kg-1; r = 0.96). Subjects trained primarily by walking and running for 9-12 mo, averaging 3.9 +/- 0.6 days/wk and 45 +/- 5 min/day at 80 +/- 5% of maximal heart rate (HRmax). Average improvement in VO2max (ml.min-1.kg-1) was 24 +/- 12% (range 0-58%). Relative improvement was not significantly different in men and women (26 +/- 12 vs. 23 +/- 12%, ml.min-1.kg-1; 21 +/- 10 vs 19 +/- 10%, l/min). When subjects were divided into three groups by age (60-62, 63-66, 67-71 yr), there were no significant differences among the groups in the relative increase in VO2max (21% vs. 19% vs. 18%, 1/min). Correlation analysis also yielded a nonsignificant relationship between improvement and age (r = -0.13). To examine the effect of initial fitness level on the adaptive response to exercise, pretraining VO2max was correlated with the absolute improvement in VO2max. This relationship was not significant in either men (r = 0.04) or women (r = -0.23). In conclusion, in healthy people aged 60-71 yr, VO2max adapts to endurance exercise training to the same relative extent as in young people, and this adaptation is independent of gender, age, and initial level of fitness.

Evaluation of benign vs malignant hepatic lesions with positron emission tomography

BACKGROUND

In most malignant cells, the relatively low level of glucose-6-phosphatase leads to accumulation and trapping of [18F]fluorodeoxyglucose (FDG) intracellularly, allowing the visualization of increased uptake compared with normal cells.

OBJECTIVES

To assess the value of FDG positron emission tomography (PET) to differentiate benign from malignant hepatic lesions and to determine in which types of hepatic tumors PET can help evaluate stage, monitor response to therapy, and detect recurrence.

DESIGN

Prospective blinded-comparison clinical cohort study.

SETTING

Tertiary care university hospital and clinic.

PATIENTS

One hundred ten consecutive referred patients with hepatic lesions 1 cm or larger on screening computed tomographic (CT) images who were seen for evaluation and potential resection underwent PET imaging. There were 60 men and 50 women with a mean (+/-SD) age of 59 +/- 14 years. Follow-up was 100%.

INTERVENTIONS

A PET scan using static imaging was performed on all patients. The PET scan imaging and biopsy, surgery, or both were performed, providing pathological samples within 2 months of PET imaging. All PET images were correlated with CT scan to localize the lesion. However, PET investigators were unaware of any previous interpretation of the CT scan.

MAIN OUTCOME MEASURES

Visual interpretation, lesion-to-normal liver background (L/B) ratio of radioactivity, and standard uptake value (SUV) were correlated with pathological diagnosis.

RESULTS

All (100%) liver metastases from adenocarcinoma and sarcoma primaries in 66 patients and all cholangiocarcinomas in 8 patients had increased uptake values, L/B ratios greater than 2, and an SUV greater than 3.5. Hepatocellular carcinoma had increased FDG uptake in 16 of 23 patients and poor uptake in 7 patients. All benign hepatic lesions (n = 23), including adenoma and fibronodular hyperplasia, had poor uptake, an L/B ratio of less than 2, and an SUV less than 3.5, except for 1 of 3 abscesses that had definite uptake.

CONCLUSIONS

The PET technique using FDG static imaging was useful to differentiate malignant from benign lesions in the liver. Limitations include false-positive results in a minority of abscesses and false-negative results in a minority of hepatocellular carcinoma. The PET technique was useful in tumor staging and detection of recurrence, as well as monitoring response to therapy for all adenocarcinomas and sarcomas and most hepatocellular carcinomas. Therefore, pretherapy PET imaging is recommended to help assess new hepatic lesions.

Carbohydrate feeding during prolonged strenuous exercise can delay fatigue

This study was undertaken to determine whether carbohydrate feeding during exercise can delay the development of fatigue. Ten trained cyclists performed two bicycle ergometer exercise tests 1 wk apart. The initial work rate required 74 +/- 2% of maximum O2 consumption (VO2 max) (range 70-79% of VO2 max). The point of fatigue was defined as the time at which the exercise intensity the subjects could maintain decreased below their initial work rate by 10% of VO2 max. During one exercise test the subjects were fed a glucose polymer solution beginning 20 min after the onset of exercise; during the other they were given a placebo. Blood glucose concentration was 20-40% higher during the exercise after carbohydrate ingestion than during the exercise without carbohydrate feeding. The exercise-induced decrease in plasma insulin was prevented by carbohydrate feeding. The respiratory exchange ratio was unchanged by the glucose feeding. Fatigue was postponed by carbohydrate feeding in 7 of the 10 subjects. This effect appeared to be mediated by prevention of hypoglycemia in only two subjects. The exercise time to fatigue for the 10 subjects averaged 134 +/- 6 min (mean +/- SE) without and 157 +/- 5 min with carbohydrate feeding (P less than 0.01).

Effect of exercise training in 60- to 69-year-old persons with essential hypertension

This study sought to determine whether 9 months of low- or moderate-intensity exercise training could decrease blood pressure (BP) in hypertensive men and women (mean age 64 +/- 3 years). Patients underwent weekly BP evaluations for 1 month to ensure that they had persistently elevated BP and then completed a maximal treadmill exercise test to exclude those with overt coronary artery disease. The low- and moderate-intensity groups trained at 53 and 73% of maximal oxygen consumption (VO2 max), respectively; however, total caloric expenditure per week was similar in both groups. VO2 max did not increase in the low-intensity group with training, but increased 28% in the moderate-intensity group. Diastolic BP decreased 11 to 12 mm Hg in both training groups. Systolic BP decreased 20 mm Hg in the low-intensity group with training, which was significantly greater than the change in the control and the moderate-intensity groups. Although systolic BP decreased 8 mm Hg in the moderate-intensity training group, this reduction was not significant. Training resulted in a somewhat lower cardiac output at rest in the low-intensity group, whereas total peripheral resistance decreased slightly in the moderate-intensity training group. Plasma and blood volumes, plasma renin levels and urinary sodium excretion did not change in either group with training. Both groups manifested lower plasma norepinephrine levels after training during standing rest, but not while supine. Thus, low-intensity training may lower BP as much or more than moderate-intensity training in older persons with essential hypertension, but the underlying mechanisms are unclear.

Decline in VO2max with aging in master athletes and sedentary men

Fifteen well-trained master endurance athletes [62.0 +/- 2.3 (SE) yr] and 14 sedentary control subjects (61.4 +/- 1.4 yr) were reevaluated after an average follow-up period of approximately 8 yr to obtain information regarding the effects of physical activity on the age-related decline in maximal O2 uptake capacity (VO2max). The master athletes had been training for 10.2 +/- 2.9 yr before initial testing and continued to train during the follow-up period. The sedentary subjects' VO2max declined by an average of 3.3 ml.kg-1.min-1 (33.9 +/- 1.7 vs. 30.6 +/- 1.6, P less than 0.001) over the course of the study, a decline of 12% per decade. In these subjects maximal heart rate declined 8 beats/min (171 vs. 163) and maximal O2 pulse decreased from 0.20 to 0.18 ml.kg-1.beat (P less than 0.05). The master athletes' VO2 max decreased by an average of 2.2 ml.kg-1.min-1 (54.0 +/- 1.7 vs. 51.8 +/- 1.8, P less than 0.05), a 5.5% decline per decade. The master athletes' maximal heart rate was unchanged (171 +/- 3 beats/min) and their maximal O2 pulse decreased from 0.32 to 0.30 ml.kg-1.beat (P less than 0.05). These findings provide evidence that the age-related decrease in VO2max of master athletes who continue to engage in regular vigorous endurance exercise training is approximately one-half the rate of decline seen in age-matched sedentary subjects. Furthermore our results suggest that endurance exercise training may reduce the rate of decline in maximal heart rate that typically occurs as an individual ages.

Time course of loss of adaptations after stopping prolonged intense endurance training

Seven endurance exercise-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Maximal O2 uptake (VO2 max) declined 7% (P less than 0.05) during the first 21 days of inactivity and stabilized after 56 days at a level 16% (P less than 0.05) below the initial trained value. After 84 days of detraining the experimental subjects still had a higher VO2 max than did eight sedentary control subjects who had never trained (50.8 vs. 43.3 ml X kg-1 X min-1), due primarily to a larger arterial-mixed venous O2 (a-vO2) difference. Stroke volume (SV) during exercise was high initially and declined during the early detraining period to a level not different from control. Skeletal muscle capillarization did not decline with inactivity and remained 50% above (P less than 0.05) sedentary control. Citrate synthase and succinate dehydrogenase activities in muscle declined with a half-time of 12 days and stabilized at levels 50% above sedentary control (P less than 0.05). The initial decline in VO2 max was related to a reduced SV and the later decline to a reduced a-vO2 difference. Muscle capillarization and oxidative enzyme activity remained above sedentary levels and this may help explain why a-vO2 difference and VO2 max after 84 days of detraining were still higher than in untrained subjects.

Isozyme-nonselective N-substituted bipiperidylcarboxamide acetyl-CoA carboxylase inhibitors reduce tissue malonyl-CoA concentrations, inhibit fatty acid synthesis, and increase fatty acid oxidation in cultured cells and in experimental animals

Inhibition of acetyl-CoA carboxylase (ACC), with its resultant inhibition of fatty acid synthesis and stimulation of fatty acid oxidation, has the potential to favorably affect the multitude of cardiovascular risk factors associated with the metabolic syndrome. To achieve maximal effectiveness, an ACC inhibitor should inhibit both the lipogenic tissue isozyme (ACC1) and the oxidative tissue isozyme (ACC2). Herein, we describe the biochemical and acute physiological properties of CP-610431, an isozyme-nonselective ACC inhibitor identified through high throughput inhibition screening, and CP-640186, an analog with improved metabolic stability. CP-610431 inhibited ACC1 and ACC2 with IC50s of approximately 50 nm. Inhibition was reversible, uncompetitive with respect to ATP, and non-competitive with respect to bicarbonate, acetyl-CoA, and citrate, indicating interaction with the enzymatic carboxyl transfer reaction. CP-610431 also inhibited fatty acid synthesis, triglyceride (TG) synthesis, TG secretion, and apolipoprotein B secretion in HepG2 cells (ACC1) with EC50s of 1.6, 1.8, 3.0, and 5.7 microm, without affecting either cholesterol synthesis or apolipoprotein CIII secretion. CP-640186, also inhibited both isozymes with IC50sof approximately 55 nm but was 2-3 times more potent than CP-610431 in inhibiting HepG2 cell fatty acid and TG synthesis. CP-640186 also stimulated fatty acid oxidation in C2C12 cells (ACC2) and in rat epitrochlearis muscle strips with EC50s of 57 nm and 1.3 microm. In rats, CP-640186 lowered hepatic, soleus muscle, quadriceps muscle, and cardiac muscle malonyl-CoA with ED50s of 55, 6, 15, and 8 mg/kg. Consequently, CP-640186 inhibited fatty acid synthesis in rats, CD1 mice, and ob/ob mice with ED50s of 13, 11, and 4 mg/kg, and stimulated rat whole body fatty acid oxidation with an ED50 of approximately 30 mg/kg. Taken together, These observations indicate that isozyme-nonselective ACC inhibition has the potential to favorably affect risk factors associated with the metabolic syndrome.

Discovery of a human liver glycogen phosphorylase inhibitor that lowers blood glucose in vivo

An inhibitor of human liver glycogen phosphorylase a (HLGPa) has been identified and characterized in vitro and in vivo. This substance, [R-(R*, S*)]-5-chloro-N-[3-(dimethylamino)-2-hydroxy-3-oxo-1-(phenylmethyl)pr opyl]-1H-indole-2-carboxamide (CP-91149), inhibited HLGPa with an IC50 of 0.13 microM in the presence of 7.5 mM glucose. CP-91149 resembles caffeine, a known allosteric phosphorylase inhibitor, in that it is 5- to 10-fold less potent in the absence of glucose. Further analysis, however, suggests that CP-91149 and caffeine are kinetically distinct. Functionally, CP-91149 inhibited glucagon-stimulated glycogenolysis in isolated rat hepatocytes (P < 0.05 at 10-100 microM) and in primary human hepatocytes (2.1 microM IC50). In vivo, oral administration of CP-91149 to diabetic ob/ob mice at 25-50 mg/kg resulted in rapid (3 h) glucose lowering by 100-120 mg/dl (P < 0.001) without producing hypoglycemia. Further, CP-91149 treatment did not lower glucose levels in normoglycemic, nondiabetic mice. In ob/ob mice pretreated with 14C-glucose to label liver glycogen, CP-91149 administration reduced 14C-glycogen breakdown, confirming that glucose lowering resulted from inhibition of glycogenolysis in vivo. These findings support the use of CP-91149 in investigating glycogenolytic versus gluconeogenic flux in hepatic glucose production, and they demonstrate that glycogenolysis inhibitors may be useful in the treatment of type 2 diabetes.

Effects of detraining on enzymes of energy metabolism in individual human muscle fibers

Muscle biopsies were obtained from three cyclists and four runners at the end of 10-24 mo of intensive training and after intervals of detraining up to 12 wk. Control samples came from four untrained persons and four former athletes. Macro mixed fiber samples were assayed for lactate dehydrogenase, adenylate kinase, glycogen phosphorylase, citrate synthase, malate dehydrogenase, beta-hydroxyacyl-CoA dehydrogenase, succinate dehydrogenase, beta-hydroxybutyrate dehydrogenase, creatine kinase, hexokinase, 1-phosphofructokinase, fructosebisphosphatase, protein, and total creatine. In the case of three trained persons and two controls, the first six of the enzymes were also measured in individual fibers. Before detraining, enzymes of oxidative metabolism were substantially higher than in controls, and differences in levels between type I and type II fibers were smaller. During detraining, oxidative enzymes were decreased in both fiber types but the type II fibers did not fall to control levels even after 12 wk. Phosphorylase increased with detraining in both fiber types. The same is true for lactate dehydrogenase and adenylate kinase, except in the case of the type I fibers of one individual. Among the other six enzymes (measured in mixed fiber samples), only hexokinase was consistently affected (decreased) by detraining.

Rapid regression of pituitary prolactinomas during bromocriptine treatment

Therapy for large prolactinomas remains controversial. Surgery is often unsuccessful in restoring endocrine function to normal. However, medical therapy with bromocriptine, a dopamine agonist, not only suppresses PRL levels, but may also lead to a reduction in tumor size. Previous reports have demonstrated radiographic evidence of tumor regression only after 3 or more months of bromocriptine therapy. We have now documented, for the first time, objective evidence of extremely rapid reduction in tumor size in two patients harboring large PRL-secreting pituitary tumors (mean pretreatment serum PRL levels, 2350 and 3900 ng/ml) who were prospectively treated with bromocriptine (7.5 mg/day) in preference to surgical intervention despite marked visual impairment in one of the patients. After 2 and 6 weeks of therapy, respectively, marked reduction in tumor size was demonstrated radiographically in both patients. Headache, visual acuity, and visual fields had improved after only 3 days. Although the mechanism of bromocriptine's antitumor activity is unclear, we believe that a large prospective trial to study the effects of bromocriptine therapy on the size of PRL-secreting macroadenomas is urgently needed to determine whether medical therapy should become the primary modality of treatment to reduce tumor size as well as restore endocrine function.

Effect of minimally invasive radioguided parathyroidectomy on efficacy, length of stay, and costs in the management of primary hyperparathyroidism

OBJECTIVE

To compare the first 20 patients who underwent minimally invasive radioguided parathyroidectomies (MIRPs) performed at the authors' institution with 20 similar patients who underwent a more conventional surgical approach for primary hyperparathyroidism.

SUMMARY BACKGROUND DATA

The technique of parathyroidectomy has traditionally involved a bilateral exploration of the neck with the intent of visualizing four parathyroid glands and resecting enlarged parathyroid glands. Parathyroid scanning using radioisotopes has evolved and now can localize adenomas in 80% to 90% of patients. MIRP combines parathyroid scanning with a hand-held intraoperative detector that guides the surgeon to the adenoma.

METHODS

Forty patients with documented primary hyperparathyroidism who underwent surgery by a single surgeon between January 1998 and May 1999 were included in this study. Twenty of these patients underwent MIRP. The technique involved injecting 20 mCi technetium-99m sestamibi 2 hours before surgery and performing a parathyroid scan. If the scan was considered positive for a single adenoma, patients were taken to the operating room and given the choice of either general anesthesia or intravenous sedation with local anesthesia. Using an incision of 4 cm or less, the dissection down to the adenoma was guided by the Navigator miniature hand-held probe. An additional 20 patients who underwent more conventional bilateral or unilateral neck exploration were chosen to match the MIRP patient population. Both groups included four patients undergoing repeat surgery for persistent or recurrent primary hyperparathyroidism and one patient with multiple endocrine neoplasia type 1 syndrome. Patient demographics, preoperative calcium and parathyroid hormone levels, operative time, total time in the operating room, time in the recovery room, complications, hospital charges for the operating room, and total hospital charges were analyzed.

RESULTS

There were no differences in patient demographics, presenting symptoms, or preoperative calcium level between patients undergoing the standard procedure versus MIRP. Operative time, total time in the operating room, operative charges, and total hospital charges were significantly reduced in the MIRP group. All 40 patients were cured of primary hyperparathyroidism. There were no recurrent laryngeal nerve injures in either group. The mean length of stay in the standard group was 1. 35 days; in the MIRP group, 65% of patients were discharged within 5 hours after surgery.

CONCLUSIONS

The MIRP technique resulted in excellent cure rates for primary hyperparathyroidism while simultaneously decreasing operative time and hospital stays. These resulted in significant cost reductions without compromising patient safety. The technique may significantly change the management of primary hyperparathyroidism.

Differences in cardiovascular adaptations to endurance exercise training between older men and women

Recent studies have shown that people in their seventh decade are able to adapt to exercise training with an increase in maximal O2 uptake (VO2max) similar in relative magnitude to that observed in young people. The purpose of this study was to determine the relative contributions of increases in stroke volume and O2 extraction to the training-induced increase in VO2max in older men and women. Fifteen men [63 +/- 3 (SE) yr] and 16 women (64 +/- 3 yr), in good health, participated in 9-12 mo of endurance exercise training at 70 to 85% of maximal heart rate for 45 min/day, 4 days/wk. VO2max increased 19% (2.35 +/- 0.1 to 2.8 +/- 0.1 l/min; P < 0.01) in the men and 22% (1.36 +/- 0.1 to 1.66 +/- 0.1 l/min; P < 0.01) in the women in response to training. In the men, stroke volume during maximal exercise was 15% higher after training, and this increase accounted for 66% of the increase in VO2max. The remainder of the increase in VO2max was accounted for by a 7% greater arteriovenous O2 content difference during maximal exercise. In contrast, training resulted in no change in stroke volume in women, in whom the entire increase in VO2max was accounted for by a greater arteriovenous O2 content difference (12.2 +/- 0.4 before vs. 14.4 +/- 0.4 ml O2/100 ml blood after; P < 0.01) during maximal exercise. There were no changes in these variables in the control subjects. The mechanisms responsible for the training-induced increase in VO2max in the older men were similar to those found in young people.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise hyperventilation in patients with McArdle's disease

This study was undertaken to determine if patients who lack muscle phosphorylase (i.e., McArdle's disease), and therefore the ability to produce lactic acid during exercise, demonstrate a normal hyperventilatory response during progressive incremental exercise. As expected these patients did not increase their blood lactate above resting levels, whereas the blood lactate levels of normal subjects increased 8- to 10-fold during maximal exercise. The venous pH of the normal subjects decreased markedly during exercise that resulted in hyperventilation. The patients demonstrated a distinct increase in ventilation with respect to O2 consumption similar to that seen in normal individuals during submaximal exercise. However their hyperventilation resulted in an increase in pH because there was no underlying metabolic acidosis. End-tidal partial pressures of O2 and CO2 also reflected a distinct hyperventilation in both groups at approximately 70-85% maximal O2 consumption. These data show that hyperventilation occurs during intense exercise, even when there is no increase in plasma [H+]. Since arterial CO2 levels were decreasing and O2 levels were increasing during the hyperventilation, it is possible that nonhumoral stimuli originating in the active muscles or in the brain elicit the hyperventilation observed during intense exercise.

Tinnitus severity, loudness, and depression

Answers to questionnaires filled out by 436 patients who visited our tinnitus clinic were analyzed. Patients were asked to report the presence or absence of depression and to rate the loudness and severity of their tinnitus. Responses to questions about tinnitus loudness and severity from 121 patients who reported current depression were compared with responses from 285 patients who reported no history of depression. There was no significant difference in reported loudness of tinnitus between patients with and without depression. However, patients with current depression scored significantly higher than patients without depression on all 12 questions relating to tinnitus severity. We conclude that depression and tinnitus severity are linked in some patients. Treatment of depression with medications and psychotherapy is likely to reduce tinnitus severity for many of these patients.

Methodological aspects of clinical trials in tinnitus: a proposal for an international standard

Chronic tinnitus is a common condition with a high burden of disease. While many different treatments are used in clinical practice, the evidence for the efficacy of these treatments is low and the variance of treatment response between individuals is high. This is most likely due to the great heterogeneity of tinnitus with respect to clinical features as well as underlying pathophysiological mechanisms. There is a clear need to find effective treatment options in tinnitus, however, clinical trials differ substantially with respect to methodological quality and design. Consequently, the conclusions that can be derived from these studies are limited and jeopardize comparison between studies. Here, we discuss our view of the most important aspects of trial design in clinical studies in tinnitus and make suggestions for an international methodological standard in tinnitus trials. We hope that the proposed methodological standard will stimulate scientific discussion and will help to improve the quality of trials in tinnitus.

Maximal vascular leg conductance in trained and untrained men

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.

Effects of detraining on responses to submaximal exercise

Seven endurance-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Heart rate, ventilation, respiratory exchange ratio, and blood lactate concentration during submaximal exercise of the same absolute intensity increased (P less than 0.05) progressively during the first 56 days of detraining, after which a stabilization occurred. These changes paralleled a 40% decline (P less than 0.001) in mitochondrial enzyme activity levels and a 21% increase in total lactate dehydrogenase (LDH) activity (P less than 0.05) in trained skeletal muscle. After 84 days of detraining, the experimental subjects' muscle mitochondrial enzyme levels were still 50% above, and LDH activity was 22% below, sedentary control levels. The blood lactate threshold of the detrained subjects occurred at higher absolute and relative (i.e., 75 +/- 2% vs. 62 +/- 3% of maximal O2 uptake) exercise intensities in the subjects after 84 days of detraining than in untrained controls (P less than 0.05). Thus it appears that a portion of the adaptation to prolonged and intense endurance training that is responsible for the higher lactate threshold in the trained state persists for a long time (greater than 85 days) after training is stopped.

Effects of aging, gender, and physical training on peripheral vascular function

BACKGROUND

Blood pressure and total peripheral resistance increase with age. However, the effect of age on vasodilatory capacity has not been characterized.

METHODS AND RESULTS

To delineate the effects of aging, gender, and physical training on peripheral vascular function, we measured blood pressure during submaximal and maximal treadmill exercise and measured blood pressure, calf blood flow, and calf conductance (blood flow/mean blood pressure) at rest and during maximal hyperemia in 58 healthy sedentary subjects (men aged 25 +/- 5 and 65 +/- 3 years and women aged 27 +/- 5 and 65 +/- 4 years) and in 52 endurance exercise-trained subjects (men aged 30 +/- 3 and 65 +/- 4 years and women aged 27 +/- 3 and 65 +/- 3 years). Systolic and mean blood pressures were higher at rest, during maximal calf hyperemia, and during submaximal exercise of the same intensity in the older than in the younger subjects of the same gender and exercise training status (p less than 0.01). The magnitude of the age-related effect on blood pressure during exercise was greater in women than in men (p less than 0.01). Diastolic blood pressure during submaximal exercise was also higher in the older than in the younger subjects (p less than 0.05) but not in women treated with estrogen replacement. In contrast, systolic and mean blood pressures during submaximal work were lower in physically conditioned subjects than in sedentary age- and gender-matched subjects (p less than 0.05) but not in older women. Increased age was associated with reduced maximal calf conductance in women (p less than 0.01) but not in men. However, calf vasodilatory capacity was higher in trained than in untrained subjects (p less than 0.01), regardless of age and gender. There was a significant inverse relation between maximal calf conductance and systolic, diastolic, and mean blood pressures during submaximal exercise (r = -0.31 to -0.53, p less than 0.01) and a direct relation between maximal calf conductance and maximal oxygen uptake (r = 0.66, p less than 0.0001).

CONCLUSIONS

Thus, for healthy subjects between the ages of 25 and 65 years, there is an interactive effect between age and gender and an independent effect of physical training on peripheral vascular function.

Chronic tinnitus as phantom auditory pain

OBJECTIVES

To investigate similarities between patients who experience chronic tinnitus or pain and to formulate treatment strategies that are likely to be effective for patients who experience phantom auditory pain.

STUDY DESIGN

A total of 160 patients rated the severity and loudness of their tinnitus and completed the State-Trait Anxiety Inventory (STAI) and an abbreviated version of the Beck Depression Inventory (aBDI). Patients received counseling, audiometric testing, and matched the loudness of their tinnitus to sounds played through headphones.

SETTING

A specialized tinnitus clinic within an urban medical center.

RESULTS

Tinnitus severity was highly correlated with patients' degree of sleep disturbance, STAI, and aBDI scores. The self-rated (on a 1-to-10 scale)--but not the matched--loudness of tinnitus was correlated with tinnitus severity, sleep disturbance, STAI, and aBDI scores.

CONCLUSIONS

The severity of chronic tinnitus is correlated with the severity of insomnia, anxiety, and depression. These relationships are the same for many patients with chronic pain. Treatment recommendations are discussed in reference to these results.

Cardiac effects of prolonged and intense exercise training in patients with coronary artery disease

The effects of intense and prolonged exercise training on the heart were studied with echocardiography in eight men with coronary artery disease with a mean age (+/- standard error of the mean) of 52 +/- 3 years. Training consisted of endurance exercise 3 times/week at 50 to 60 percent of the measured maximal oxygen uptake for 3 months followed by exercise 4 to 5 days/week at 70 to 80 percent of maximal oxygen uptake for 9 months. Maximal oxygen uptake capacity increased by 42 percent (26 +/- 1 versus 37 +/- 2 ml/kg per min; p less than 0.001). Heart rate at rest and submaximal heart rate and systolic blood pressure at a given work rate were significantly lower after training. Systolic blood pressure at the time of maximal exercise increased (145 +/- 9 before versus 166 +/- 8 mm Hg after training; probability [p] less than 0.01). Left ventricular end-diastolic diameter was increased after 12 months of training (from 47 +/- 1 to 51 +/- 1 mm; p less than 0.01). Left ventricular fractional shortening and mean velocity of circumferential shortening decreased progressively in response to graded isometric handgrip exercise before training but not after training. At comparable levels of blood pressure during static exercise, mean velocity of circumferential shortening was significantly higher after training (0.76 +/- 0.04 versus 0.98 +/- 0.07 diameter/sec, p less than 0.01). No improvement in echocardiographic or exercise variables was observed over a 12 month period in another group of five patients who did not exercise. Thus the data suggest that prolonged and vigorous exercise training in selected patients with coronary artery disease can elicit cardiac adaptations.

Blood pressure and hemodynamic responses after exercise in older hypertensives

Recently, systolic and diastolic blood pressure have been reported to be significantly lower for several hours after exercise than when measured at rest before exercise in individuals with essential hypertension. We sought to determine the hemodynamic mechanism underlying this reduction in blood pressure. Twenty-four men and women 60-69 yr of age with persistent essential hypertension completed one of the following protocols: exercise at 50% of maximum O2 consumption (VO2 max) followed by 1 h of recovery, exercise at 70% of VO2 max followed by 3 h of recovery, or a 4-h control study. Systolic pressure was significantly lower during recovery after both intensities of exercise, but diastolic pressure was unchanged. The lower blood pressure was primarily due to a reduction in cardiac output, since total peripheral resistance was increased throughout both recovery periods. Cardiac output was reduced in recovery because of a reduction in stroke volume. Heart rate was above, or no different from, that at rest before exercise. Changes in plasma volume could not entirely account for the reduction in stroke volume. Therefore, other mechanisms altering venous return and/or myocardial contractility appear to be responsible for the reduction in systolic blood pressure evident after a single bout of submaximal exercise in individuals with essential hypertension.