Simvastatin increases serum osteocalcin concentration in patients treated for hypercholesterolaemia

Animal studies, experimental models on cell lines, and epidemiological case-control studies have all suggested the possibility that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors have a beneficial effect on bone metabolism. However, all epidemiological studies are not prospective in nature and based on either measurement of bone mineral density or fracture risk. They also differ in recruitment criteria, definition of statin exposure, and outcome assessment. We performed a first prospective study using specific biochemical bone markers on 17 hypercholesterolaemic non-osteoporotic subjects treated with a therapeutic dose of simvastatin 20 mg daily for 4 weeks. Our results show that serum osteocalcin concentration increased significantly (p-value < 0.05) 4 weeks after therapy, whereas other bone markers including serum bone-specific alkaline phosphatase activity, urine deoxypyridinoline, and urine cross-linked N-telopeptides of type I collagen did not show any significant changes. Our data support that simvastatin causes a beneficial effect on bone metabolism as reflected by an increase in serum osteocalcin concentration. This added beneficial effect of statins on bone metabolism could potentially allow statins to become the first effective anabolic agent for the treatment of osteoporosis. We urge that priority should be given to a randomised controlled study to re-evaluate this group of drugs.

Turning on and off with excitation: the role of spike-timing asynchrony and synchrony in sustained neural activity

Delay-related sustained activity in the prefrontal cortex of primates, a neurological analogue of working memory, has been proposed to arise from synaptic interactions in local cortical circuits. The implication is that memories are coded by spatially localized foci of sustained activity. We investigate the mechanisms by which sustained foci are initiated, maintained, and extinguished by excitation in networks of Hodgkin-Huxley neurons coupled with biophysical spatially structured synaptic connections. For networks with a balance between excitation and inhibition, a localized transient stimulus robustly initiates a localized focus of activity. The activity is then maintained by recurrent excitatory AMPA-like synapses. We find that to maintain the focus, the firing must be asynchronous. Consequently, inducing transient synchrony through an excitatory stimulus extinguishes the sustained activity. Such a monosynaptic excitatory turn-off mechanism is compatible with the working memory being wiped clean by an efferent copy of the motor command. The activity that codes working memories may be structured so that the motor command is both the read-out and a direct clearing signal. We show examples of data that is compatible with our theory.

Stationary bumps in networks of spiking neurons

We examine the existence and stability of spatially localized "bumps" of neuronal activity in a network of spiking neurons. Bumps have been proposed in mechanisms of visual orientation tuning, the rat head direction system, and working memory. We show that a bump solution can exist in a spiking network provided the neurons fire asynchronously within the bump. We consider a parameter regime where the bump solution is bistable with an all-off state and can be initiated with a transient excitatory stimulus. We show that the activity profile matches that of a corresponding population rate model. The bump in a spiking network can lose stability through partial synchronization to either a traveling wave or the all-off state. This can occur if the synaptic timescale is too fast through a dynamical effect or if a transient excitatory pulse is applied to the network. A bump can thus be activated and deactivated with excitatory inputs that may have physiological relevance.

Factors predicting the age when type 2 diabetes is diagnosed in Hong Kong Chinese subjects

OBJECTIVE

To examine the factors predicting age at diagnosis of type 2 diabetes in Hong Kong Chinese.

RESEARCH DESIGN AND METHODS

The relationships between age at diagnosis and parental history of diabetes as well as an array of clinical and metabolic factors were examined using a hospital clinic-based diabetes registry involving 3,414 index patients with type 2 diabetes Patterns of age at diagnosis in successive generations were also examined using 21 affected child-parent pairs and 7 affected child-parent-grandparent trios.

RESULTS

Approximately 29% of the index patients were diagnosed with type 2 diabetes at < or = 35 years of age (hereby defined as early-onset). Compared with the patients diagnosed at >35 years of age (hereby defined as late-onset) the early-onset patients had higher rates of positive paternal (16 vs. 5%) and maternal (22 vs. 12%) history of diabetes (both at P < 0.01) and had poorer metabolic profiles. In the overall index patients, male sex, higher HbA1c waist-to-hip ratio (WHR), and systolic blood pressure (sBP); lower HDL cholesterol level; and a positive paternal was well as maternal history of diabetes predicted younger age at diagnosis. More senior age and higher BMI and diastolic blood pressure predicted olderq age at diagnosis. Predictors for younger age at diagnosis in the male patients were higher HbA1c and sBP and a positive paternal history of diabetes Predictors for younger age at diagnosis in the female patients were higher HbA1c WHR, and sBP and a paternal as well as maternal history of diabetes. In the affected child parent pairs and clild-parent-grandparent trios there was a decrease in age at diagnosis in successive generations.

CONCLUSIONS

Our data indicate that both familial (possibly genetic) and metabolic factors affect the age of onset of type 2 diabetes in the Chinese population. The results also suggest an onset and progression pattern of the disease that is compatible with the phenomenon of anticipation.

Outcomes of screening for diabetes in high-risk Hong Kong Chinese subjects

OBJECTIVE

To examine the significance of individual risk factors on the development of diabetes in subjects who underwent screening for diabetes.

RESEARCH DESIGN AND METHODS

A total of 1,649 Chinese subjects underwent screening for diabetes. They were asymptomatic but had known risk factors for diabetes, including a positive family history of diabetes, a past history of gestational diabetes, obesity, hypertension, and/or dyslipidemia. Another 799 age-matched subjects from the community who had no risk factors for diabetes were used as the comparison group.

RESULTS

Of the 1,649 subjects who underwent screening, 241 (14.6%) had diabetes. In these subjects, 989 (60.0%) had 1 risk factor, 502 (30.4%) had 2 risk factors, 141 (8.6%) had 3 risk factors, and 17 (1.0%) had 4 or 5 risk factors for diabetes. Of the 799 control subjects, 29 (3.6%) had diabetes. Compared with the comparison group, the odds ratio (95% CI) of having diabetes after adjustment for age was 5.2 (3.5-7.7) in the 1,649 subjects with known risk factors. The odds ratio of having diabetes increased from 3.7 in subjects with 1 risk factor to 28.4 in subjects with 4 or 5 risk factors.

CONCLUSIONS

In men, age, BMI, family history of diabetes, and dyslipidemia, and in women, age, BMI, hypertension, dyslipidemia, total cholesterol, and history of gestational diabetes are associated with increased odds of developing diabetes. These risk factors have additive effects on the odds of having diabetes. Early and regular screening for diabetes and other cardiovascular risk factors is essential in these high-risk individuals.

Diabetes in Hong Kong Chinese: evidence for familial clustering and parental effects

OBJECTIVE

To investigate transmission patterns of diabetes and their relationships with clinical characteristics in Hong Kong Chinese patients with late-onset (age > or =35 years) type 2 diabetes.

RESEARCH DESIGN AND METHODS

This study involved 2,310 patients consecutively selected from a hospital clinic-based diabetes registry. These patients all reported the diabetes status of their parents as well as siblings.

RESULTS

Approximately 36% of the 2,310 patients reported at least 1 affected parent or sibling (25 and 21% reported at least 1 diabetic parent and sibling, respectively). These patients, irrespective of their sex, were more likely to have a diabetic mother than a diabetic father (17 vs. 13% of the male patients and 18 vs. 9% of the female patients, P<0.01). The male patients were more likely than the female patients to have a diabetic father (13 vs. 9%, P<0.01). The female patients with a diabetic mother were found to have higher levels of plasma total cholesterol compared with the female patients with a diabetic father in multiple comparisons with adjustment for significance (5.56+/-1.30 vs. 5.09+/-0.95 mmol/l, P<0.05). In 2-group comparisons, there was also evidence that the male patients with a diabetic father had higher BMI values than the male patients with a diabetic mother (25.9+/-3.5 vs. 25.0+/-3.5 kg/m2, P<0.05).

CONCLUSIONS

We found familial clustering of diabetes in the Hong Kong Chinese population as well as a significant maternal influence and a male sex-specific paternal effect. We suggest that both maternal and paternal factors may be implicated in the development of type 2 diabetes in the Chinese population.

Treatment of Chinese acromegaly with a combination of bromocriptine and octreotide

BACKGROUND

Good results have been reported with combined use of octreotide and bromocriptine in acromegalic Caucasians. Data concerning the efficacy and tolerability of this combination treatment in Chinese acromegalic patients are scanty.

AIM

The aim of this study was to assess the efficacy and tolerability of combined therapy using bromocriptine and octreotide in the treatment of acromegaly in Chinese patients and to compare the cost-effectiveness of various regimes.

METHODS

Sixteen Chinese acromegalic patients with growth hormone (GH) concentration not suppressible to below 5 mU/L (2 microg/L) during an extended OGTT were recruited to undergo four phases of the study. During the study period, the patients were given bromocriptine alone, bromocriptine and low dose octreotide, bromocriptine and medium dose octreotide, and medium dose octreotide alone. Plasma concentrations of GH and insulin-like growth factor-1 (IGF-1) were measured before and after the completion of each phase.

RESULTS

The number of patients reaching target GH concentrations was significantly higher when treated with octreotide compared to baseline (p<0.05). Bromocriptine alone had a significant effect but not to the extent of octreotide alone. A combination of low dose octreotide and bromocriptine is as efficacious in the treatment of acromegaly as high dose octreotide. None of the patients suffered from serious adverse effects.

CONCLUSION

The results confirmed the usefulness and tolerability of bromocriptine and octreotide in Chinese acromegalics. The most cost-effective regime in this study was a combination of low dose octreotide and bromocriptine.

Dynamics of spiking neurons with electrical coupling

We analyze the existence and stability of phase-locked states of neurons coupled electrically with gap junctions. We show that spike shape and size, along with driving current (which affects network frequency), play a large role in which phase-locked modes exist and are stable. Our theory makes predictions about biophysical models using spikes of different shapes, and we present simulations to confirm the predictions. We also analyze a large system of all-to-all coupled neurons and show that the splay-phase state can exist only for a certain range of frequencies.

Mitochondrial DNA A3243G mutation in patients with early- or late-onset type 2 diabetes mellitus in Hong Kong Chinese

BACKGROUND AND OBJECTIVES

The mitochondrial DNA A to G mutation at nucleotide 3243 (mt3243) is associated with a subtype of diabetes characterized by maternal transmission and deafness. We have previously reported a 2.7% prevalence of this mutation in a cohort of young patients with either type 1 or type 2 diabetes. In this study, we aimed to confirm this finding by examining for the prevalence of this mutation in a large-scale study.

SUBJECTS AND METHODS

Nine hundred and six unrelated Chinese patients with type 2 diabetes and 213 nondiabetic controls were studied. The presence of mt3243 mutation was determined by polymerase chain reaction amplification and ApaI digestion.

RESULTS

This mutation was found in four of 133 (3.0%) patients with early onset (</= 40 years) diabetes who also had a positive maternal family history, and in one of 348 (0.3%) patients with late-onset (> 40 years) diabetes and no family history. Basal pancreatic beta-cell function, as assessed by fasting plasma C-peptide, was variable amongst mutation carriers, and did not correlate with the level of heteroplasmy of mutation.

CONCLUSIONS

In agreement with most studies, our results suggest that despite the high prevalence of positive maternal family history of diabetes amongst our type 2 diabetic patients, mt3243 mutation was not a major cause of diabetes in either early- or late-onset diabetic patients in Hong Kong. The role of other genetic, environmental and intrauterine factors needs further investigation.

Thyroid function and psychiatric morbidity in patients with manic disorder receiving lithium therapy

Euthyroid hyperthyroxinemia as a result of a transient increase in thyroid-stimulating hormone (TSH) levels may contribute to the development of manic disorder. Lithium has a potent short-term antithyroidal effect that may account for its antimanic action. The thyroid function and psychiatric morbidity of 46 adult patients with manic disorder were assessed prospectively before and 1 and 6 months after lithium treatment. At baseline, the free thyroxine level (FT4, 16.23 +/- 3.11 pmol/L) was at the high end of the normal range, whereas the free triiodothyronine (FT3, 4.24 +/- 0.65 pmol/L) and TSH (1.47 +/- 0.73 mIU/L) levels were within the normal range. All patients were clinically euthyroid, but five of them (11%) had elevated FT4 levels. Baseline FT3 and FT4 levels were positively correlated with past psychiatric morbidity. The FT4 level at baseline and after 1 month of treatment was positively correlated with scores on the Brief Psychiatric Rating Scale (p < 0.02) and negatively correlated with scores on the Global Assessment Scale (p < 0.005). During the first month of treatment, the reduction of FT3 and FT4 levels was significantly correlated with a decrease in psychiatric symptoms. By 6 months, the FT3 level was no longer significantly different from that at the baseline, but FT4 levels remained significantly lower. The TSH level increased progressively from baseline to 6 months. Multilevel models showed that FT4 and serum lithium levels were positively and negatively associated with psychiatric symptoms, respectively. The findings of the study lend support to the notion that euthyroid hyperthyroxinemia contributes to acute mania and suggest that lithium's short-term antimanic action may be mediated by its antithyroid effect.

Glycaemic control in type 2 diabetes: the impact of body weight, beta-cell function and patient education

We examined the determinants of glycaemic control in a consecutive cohort of 562 newly-referred Chinese type 2 diabetic patients (57% women) during a 12-month period. All patients underwent a structured assessment with documentation of clinical and biochemical characteristics. Pancreatic beta-cell function was assessed by fasting plasma C-peptide concentration. Insulin deficiency was defined as fasting plasma C-peptide <0.2 pmol/ml. Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA) based on a product of fasting plasma glucose and insulin concentrations. Treatment was considered appropriate when insulin-deficient patients were treated with insulin and non-insulin-deficient patients were treated with oral agents or diet. Mean (+/-SD) age was 54.3+/-13.8 years (range 17-87 years) and disease duration was 5.0+/-5.9 years. At the time of referral, 70.5% (n=396) were on drug therapy (9% on insulin and 62.8% on oral agents), 20.6% (n=116) were on diet and 9% (n=50) had not received any form of treatment. The mean HbA(lc) was 8.4+/-2.3%. The geometric mean (x// antilog SD) of IR was 4.62x//2.51 (range 0. 63-162.7) and correlated only with waist : hip ratio (WHR, p=0.008). The geometric mean of plasma C peptide was 0.47x//2.89 nmol/l and correlated with BMI (p<0.001). Glycated haemoglobin was correlated positively with age (p=0.013), disease duration (p<0.001), IR (p<0. 001) and negatively with BMI (p<0.001). Glycated haemoglobin was lower in patients who had seen a dietitian (7.9% vs. 8.7%, p<0.001) or diabetes nurse (7.8% vs. 8.7%, p<0.001) or who performed self blood glucose monitoring (7.9% vs. 8.6%, p=0.001) and higher among smokers (8.9% vs. 8.2%, p=0.003). Compared to insulin-deficient patients (n=118), non-insulin-deficient patients (n=413) had features resembling that of the Metabolic Syndrome with increased WHR (p=0.005), blood pressure (p<0.001), BMI (p=0.001) and were older (p=0.04). Amongst the insulin-deficient patients, 27% were treated with oral agents or diet. Patients receiving appropriate therapy (n=362) had a lower HbA(lc) than those treated inappropriately (n=173) (8.2% vs. 8.7%, p=0.02). On multivariate analysis, short disease duration (p<0.001), low IR (p<0.001), high BMI (p=0.001), diabetes education (p<0.001), lack of smoking (p=0. 014) and choice of appropriate treatment (p=0.009) were the independent determinants of good glycaemic control.

Spontaneous necrosis of parathyroid adenoma: biochemical and imaging follow-up for two years

We report a patient with a biochemically and radiologically confirmed parathyroid adenoma, which underwent spontaneous resolution by necrosis. The patient was followed-up over the subsequent two years during which time the tumour and hypercalcaemia recurred. Sequential radiological and biochemical changes at the time of diagnosis, spontaneous necrosis and recurrence are documented fully.

Molecular genetics of diabetes mellitus in Chinese subjects: identification of mutations in glucokinase and hepatocyte nuclear factor-1alpha genes in patients with early-onset type 2 diabetes mellitus/MODY

AIMS

To examine the prevalence of identified MODY-related genes in Chinese subjects with early onset Type 2 diabetes mellitus and a positive family history of diabetes and to look for possible associations between the gene mutations and the development of diabetes.

METHODS

Ninety-two unrelated Chinese subjects with diabetes diagnosed before the age of 40 years who had a positive family history of diabetes were screened for mutations in hepatocyte nuclear factors (HNF-1alpha and HNF-4alpha) and glucokinase genes by direct sequencing. The family members of patients with mutations and 100 healthy controls were also examined.

RESULTS

Mutations in the HNF-1alpha and the glucokinase genes were found in 5% and 3% of the diabetic subjects, respectively but no mutations were found in the coding region of the HNF-4alpha gene. Three mutations found in the glucokinase gene were novel missense mutations (I110T, A119D and G385V). The mutations in the HNF-1alpha gene were also new and included four missense mutations (G20R, R203H, S432C, I618M) and one splice acceptor site mutation (IVS2nt-1G-->A). Patients with mutations in these genes were clinically heterogeneous with respect to phenotype and basal pancreatic beta cell function.

CONCLUSIONS

Genetic factors such as mutations in the HNF-1alpha and glucokinase genes may be important in the development of diabetes in Chinese people, especially when the disease is of early onset.

Plasma insulin, growth hormone, cortisol, and central obesity among young Chinese type 2 diabetic patients

OBJECTIVE

To examine the relationships between central obesity, insulin resistance index, plasma insulin, growth hormone (GH), and cortisol concentrations in 90 young Chinese type 2 diabetic patients (aged 33+/-5 years) and 104 age- and sex-matched control subjects (aged 32+/-9 years).

RESEARCH DESIGN AND METHODS

Young Chinese diabetic patients (aged <40 years) were recruited from the Prince of Wales Hospital. Blood pressure, height, weight, and waist and hip circumferences were determined. Venous blood was sampled for measurements of fasting plasma glucose, HbA1c, lipids, creatinine, insulin, GH, and cortisol. A 24-h urine was assayed for urinary albumin excretion (UAE). General and central obesity was represented by BMI and waist circumference, respectively. Insulin resistance index was estimated as a product of fasting plasma insulin and glucose concentrations.

RESULTS

Compared with control subjects, diabetic patients were more obese, hyperglycemic, and had worse lipid profile, higher blood pressures, UAE, insulin resistance index, plasma insulin, and cortisol concentrations (all P < 0.001) but lower GH concentrations (P < 0.05). When analyzed as a whole group (n = 194), increasing quartiles of waist circumference were associated with increasing trends of insulin resistance index, plasma insulin, and cortisol concentrations (all P < 0.01) but a decreasing trend of plasma GH concentration (P < 0.05). Using stepwise multiple regression analysis, waist circumference was only associated with sex variable (being higher in men) in the control subjects. In the diabetic group, 51% of waist circumference was independently related to male sex and increased plasma insulin and cortisol concentrations as well as reduced plasma GH levels.

CONCLUSIONS

In young Chinese type 2 diabetic patients, hyperinsulinemia, hypercortisolemia, and reduced plasma GH levels were closely associated with central obesity. Based on these findings, we postulate that maladaptive hormonal responses to rapid changes in lifestyle may have led to obesity and type 2 diabetes in these young patients. Alternatively, lifestyle-related obesity may have given rise to these hormonal changes. More studies are required to delineate the nature of these relationships.

Effects of fatigue on the temporal neuromuscular control of vastus medialis muscle in humans

The effects of muscle fatigue on the temporal neuromuscular control of the vastus medialis (VM) muscle were investigated in 19 young male subjects. The electromyogram (EMG) activities of VM and the force generation capacities of the quadriceps muscle were monitored before and after a fatigue protocol. In response to light signals, which were triggered randomly, the subjects made three maximal isometric knee extensions. This was then followed by the fatigue protocol which consisted of 30 isometric maximal voluntary contractions at a sequence of 5-s on and 5-s off. Immediately after the exercise to fatigue, the subjects performed another three maximal isometric contractions in response to the light signals. The effects of fatigue on the temporal neuromuscular control were then investigated by dividing the total reaction time (TRT) into premotor time (PMT) and electromechanical delay (EMD). The TRT was defined as the time interval between the light signal and the onset of the knee extension force. The PMT was defined as the time from the light signal to the onset of EMG activities of VM, and EMD as the time interval between onset of EMG activities to that of force generation. Following the contractions to fatigue there was a significant decrease in peak force (Fpeak, P = 0.016), an increase in the root mean square (rms)-EMG: Fpeak quotient (P = 0.001) but an insignificant change in the median frequency (P = 0.062) and rms-EMG (P = 0.119). Significant lengthening of mean EMD was found after the fatigue protocol [0.0396 (SD 0.009) vs. 0.0518 (SD 0.016) s P<0.001]. The lengthening of EMD in VM would affect the stabilizing effect of the patella during knee extension. The faster mean PMT [0.2445 (SD 0.093) vs. 0.2075 (SD 0.074) s, P = 0.042] following the fatigue protocol might have compensated for the lengthened EMD and contributed to the insignificant change in the mean TRT [0.284 (SD 0.09) vs. 0.259 (SD 0.073) s, P = 0.164]. This was probably related to the low level of fatigue (15% decrease in force) and the stereotyped nature of the action such that the effects of the fatigue on neuromuscular control were likely to have been attributable to peripheral processes.

Noise shaping in populations of coupled model neurons

Biological information-processing systems, such as populations of sensory and motor neurons, may use correlations between the firings of individual elements to obtain lower noise levels and a systemwide performance improvement in the dynamic range or the signal-to-noise ratio. Here, we implement such correlations in networks of coupled integrate-and-fire neurons using inhibitory coupling and demonstrate that this can improve the system dynamic range and the signal-to-noise ratio in a population rate code. The improvement can surpass that expected for simple averaging of uncorrelated elements. A theory that predicts the resulting power spectrum is developed in terms of a stochastic point-process model in which the instantaneous population firing rate is modulated by the coupling between elements.

Assessing muscle stiffness from quiet stance in Parkinson's disease

In previous studies, we developed a postural stiffness measure that is extracted from foot center-of-pressure (COP) trajectories from quietly standing individuals and is based on an analytical mechanical model of posture control. Here we apply this measure to patients with Parkinson's disease (PD). We correlated the postural stiffness measure with different clinical rating scales, obtained from patients. Kendall's rank correlation was highly significant between the stiffness measure and rigidity, bradykinesia, posture impairment, gait, and leg agility, respectively, as rated by the Unified Parkinson's Disease Rating Scale. These results provide further evidence that a higher intrinsic muscle stiffness may contribute to the aforementioned clinically defined symptoms. From a clinical standpoint, this work indicates that the proposed postural stiffness measure may be useful as an assessment tool for the evaluation of PD patients subsequent to pharmacological and surgical treatment.

Clinical characteristics of acromegaly in Hong Kong

This study analyses the clinical characteristics of acromegalic patients in Hong Kong. All patients with acromegaly under follow up in Prince of Wales Hospital, Hong Kong between January 1984 and December 1992 were reviewed retrospectively. Detailed hospital notes were available for review in 28 out of 34. Of the 28 patients with full records available, 27 were Chinese and 1 was Nepalese. There were 8 (28.6%) males and 20 (71.4%) females. The mean age (+/- SD) at presentation was 51.2+/-16.8 years (range: 28 to 84 years) (male, 49.9+/-13.9 years [range: 28-66]; female, 51.7+/-18.1 years [range: 31-84]; p-value: NS). The commonest mode of presentation (n=22, 78.6%) was clinical suspicion by medical staff during consultation for other conditions, acromegaly being later confirmed. The estimated duration of symptoms, before diagnosis, was 14 years (range: 1 to 30 years). CT scan imaging of the pituitary gland showed that 12 patients (42.9%) had pituitary macro-adenomas (> or =1 cm), 3 (10.7%) had micro-adenomas (<1 cm), 6 (21.4%) had normal imaging, 1 (3.6%) had an empty sella and 6 (21.4%) had suspicious but inconclusive lesions in the pituitary gland. Surgery was offered as initial treatment to all patients. 4 to 6 weeks after surgery, if the maximal growth hormone response following glucose loading exceeded 10 microg/L, radiotherapy was offered. Of the 28 patients, 13 received surgery and radiotherapy, 2 surgery only, 4 radiotherapy only, 4 no treatment and 5 defaulted. At presentation, 50% had some abnormality of glucose tolerance. The mean early morning fasting baseline growth hormone was 52.8+/-37.0 microg/L (mean +/- SD, median: 48.1 microg/L) and the maximal growth hormone response during an extended oral glucose tolerance test was 63.2+/-34.9 microg/L (median: 61.3 microg/L). Forty five percents of patients had a maximal growth hormone response exceeding 60 microg/L. Of the 19 patients who underwent surgery and/or radiotherapy, 15 had their pituitary function reassessed 6 months after intervention. Their early morning fasting growth hormone and maximal growth hormone response in an extended oral glucose tolerance test were 21.3+/-25.8 and 35.4+/-37.5 microg/L, respectively. In conclusion, acromegaly in Hong Kong has an estimated annual incidence of 3.8 per million. There is a female preponderance, tendency to late presentation (>10 years) and low number of large tumors. Up to 80% were referred following observer suspicion.

Gynaecomastia as a presenting feature of thyrotoxicosis

The association between gynaecomastia and thyrotoxicosis is well recognised. However, the reported frequency of the association is variable, partly depending upon the defining criteria used. Here we report two patients with thyrotoxicosis in whom gynaecomastia was the presenting feature. Both patients had other contributing factors, which are assumed to have predisposed to gynaecomastia. In both patients, the gynaecomastia resolved with successful treatment of the thyrotoxicosis. When gynaecomastia is a presenting, or prominent feature of thyrotoxicosis, the possibility of additional underlying pathology should be considered.

Frequency control in synchronized networks of inhibitory neurons

We analyze the control of frequency for a synchronized inhibitory neuronal network. The analysis is done for a reduced membrane model with a biophysically based synaptic influence. We argue that such a reduced model can quantitatively capture the frequency behavior of a larger class of neuronal models. We show that in different parameter regimes, the network frequency depends in different ways on the intrinsic and synaptic time constants. Only in one portion of the parameter space, called phasic, is the network period proportional to the synaptic decay time. These results are discussed in connection with previous work of the authors, which showed that for mildly heterogeneous networks, the synchrony breaks down, but coherence is preserved much more for systems in the phasic regime than in the other regimes. These results imply that for mildly heterogeneous networks, the existence of a coherent rhythm implies a linear dependence of the network period on synaptic decay time and a much weaker dependence on the drive to the cells. We give experimental evidence for this conclusion.

Effects of lithium therapy on bone mineral metabolism: a two-year prospective longitudinal study

Many studies showed an increased occurrence of primary hyperparathyroidism during lithium therapy. We studied 53 patients receiving lithium therapy prospectively for 2 yr. Serum PTH levels were unequivocally elevated. The baseline PTH level was 2.8 +/- 1.2 pmol/L and increased progressively to 3.9 +/- 1.5 pmol/L after 2 yr (P < 0.0005). There was no change in serum calcium, alkaline phosphatase, inorganic phosphate concentrations or tubular reabsorption of phosphate in relation to glomerular filtration rate. Fasting urinary reabsorption of calcium increased significantly (P < 0.0005), which was concordant with the PTH change. Fasting and 24-h urinary excretion of calcium decreased significantly (P < 0.0005), suggesting reduced, rather than enhanced, bone resorption as in primary hyperparathyroidism. This may be the main mechanism in maintaining normocalcemia, despite PTH elevation, during lithium therapy.

Antibodies to glutamic acid decarboxylase in young Chinese diabetic patients

Antibodies to glutamic acid decarboxylase (GAD) are a useful autoimmune marker for type 1 diabetes mellitus in Caucasians. We examined antibodies to GAD and their relationships with clinical features and pancreatic beta cell function in 140 young Chinese diabetic patients. Over an 18-month period beginning in 1995, 140 young Chinese diabetic subjects with age of onset of disease < or = 35 years and age < 40 years were recruited consecutively, irrespective of their modes of presentation. Clinical features, antibodies to GAD and pancreatic beta cell function (using a glucagon stimulation test) were examined. Increased levels of antibodies to GAD (> 18 units) were detected in 12.1% (n = 17) of these subjects. Forty-three (31%) patients had a classical type 1 presentation and 65 (46%) patients were insulin-deficient based on post-glucagon plasma C-peptide levels. Patients who were insulin-deficient and had a type 1 presentation had the highest prevalence of antibodies to GAD (29.0%) compared with patients who had a type 2 presentation and were non-insulin deficient (6.4%, P = 0.003). Patients who had antibodies to GAD had lower body mass index and waist-hip ratio, earlier onset of disease, lower blood pressure, plasma triglyceride and C-peptide, and higher concentrations of plasma high-density lipoprotein cholesterol and glycated haemoglobin, and were more likely to require drug treatment, compared with those without antibodies to GAD. In conclusion, there was a low prevalence of antibodies to GAD in Chinese young diabetic patients although such antibodies remained a relatively specific marker for insulin deficiency and acute presentation. Causes other than autoimmunity should be sought to explain the high prevalence of insulin deficiency in these young Chinese patients.

Torsion of intraperitoneal renal transplants: imaging appearances

OBJECTIVE

Torsion of a renal transplant is a rare complication with nonspecific clinical manifestations. Prompt detection is necessary to allow surgical treatment and to preserve renal function. We describe the radiologic appearances of torsion of intraperitoneal renal transplants in patients who have undergone simultaneous renal and pancreatic transplantation or dual renal transplantation.

CONCLUSION

Renal transplant torsion should be suspected when a change in renal axis associated with abnormal perfusion occurs in an intraperitoneal kidney.