Microtubule-associated protein-2 in the rat testis: a novel site of expression.

The testis is one of the most abundant sources of microtubule networks. These networks include mitotic and meiotic spindles, the spermatid manchette and axoneme, and the Sertoli cell cytoskeleton. Microtubules are composed of alpha- and beta-tubulin subunits that are polymerized and stabilized by a variety of microtubule-associated proteins (MAPs). One of these, MAP2, has been extensively characterized as a brain-specific protein with the capacity to bind tubulin, cAMP-dependent kinase, and calmodulin. MAP2 mRNA is processed into at least two variants encoding proteins designated MAP2a, MAP2b, and MAP2c. Of the 5.7 kb of coding sequence in the 9-kb mRNA that encodes MAP2a and MAP2b, a deletion of approximately 4 kb produces mRNA encoding MAP2c, which consists of only the N- and C- terminal regions of MAP2b. To determine whether MAP2 was present in the rat testis, microtubule preparations were isolated from adult rat testis and brain by means of taxol-mediated polymerization and analyzed by gel filtration, ELISA, and Western blotting using polyclonal and monoclonal antibodies reactive with MAP2. A 74-kDa protein corresponding to MAP2c was detected in the testis. These results were confirmed by Northern blot analysis of total RNA from adult rat brain and testis with cDNA probes that distinguish between the known MAP2 splice variants. The predominant mRNAs in testis of 6 kb and 2.5-3.5 kb corresponded to MAP2c. A single 6-kb mRNA with the potential to encode MAP2c was detected in enriched preparations of immature Sertoli cells and adult Leydig cells. Round spermatids contained at least two MAP2 mRNAs between approximately 2.5 and 3.5 kb in size that displayed a stage-specific pattern of expression. Immunohistochemistry showed a MAP2-like protein in both somatic and germ cells, with a particularly distinct localization within the cytoplasm of primary and secondary spermatocytes at stage XIV of the seminiferous cycle during meiotic metaphase. In addition to cytoplasmic staining, a novel localization of this protein was observed in the nucleus of many testicular cells.

Continuing medical education: a personal view.

Over many generations doctors have kept up to date in ways which reflect their own learning styles. The current fashion for formalised and policed continuing medical education may prove ineffective unless it is recognised that individual needs must be taken into account. Attendance at formal courses based on lectures and papers may not suit a large proportion of those who attend to acquire the necessary points to satisfy their royal college. The ability to show that health care teams are up to date should come from effective clinical audit, which should also identify local educational needs.

Comparison of teachers at a 'traditional' and an 'innovative' medical school.

A 50% random sample (n = 186) of teaching staff at a 'traditional' medical school and all staff (n = 205) at an 'innovative' school were surveyed on their attitudes to teaching and teacher training. Response rates were 80% and 93% respectively. Staff at both institutions were predominantly men, highly experienced and active as teachers. Though only a minority had undergone recent teacher training, some 95% rated their teaching as 'average' or 'above average'. High levels of enthusiasm for teaching were detected in both schools. Staff at the 'innovative' school were more positive about the rewards for teaching. There was a common perception that formal training would improve the quality of teaching, though a third would not wish to participate. When developing strategies to enhance the quality of medical teaching, it is important to appreciate the existing attitudes of teachers. This survey indicates that inflated views of their own teaching ability, a perceived lack of reward for teaching, and ambivalence towards formal teacher training are three problem areas which need to be considered.

The Commonwealth doctor of medicine: a degree of uncertainty.

The degree of doctor of medicine (MD) is awarded by many universities in the British Commonwealth as a senior, postgraduate, research thesis-based degree. Some of its features are that it is limited to medical graduates of the same university, but that the research on which the thesis is based need not be conducted at the university awarding the degree and that there is no requirement for formal supervision of candidates. These characteristics, and its close similarities with the master of surgery (ChM) degree, may be responsible for the confusion that exists about its quality and status in relation to the doctorate of philosophy (PhD) and the 'higher' doctorates like doctor of science (DSc). There is also uncertainty about its role in the training and selection of clinical consultants and physician scientists.

Attitudes to teaching among teachers at a British medical school.

A random sample of clinical teachers at a British medical school was surveyed by postal questionnaire to assess their attitudes to teaching and to teacher training. The response rate among the 186 teachers sampled was 80%. A high degree of enthusiasm for teaching was detected despite a perception that teaching received neither sufficient priority within the medical school nor due recognition within its reward structure. Feelings were mixed concerning the quality of training which graduates received. However, only 5% of teachers believed their own teaching ability to be below average. This survey revealed considerable support for the concept of training courses for medical teachers, though feelings were mixed as to whether such courses should be compulsory. These findings are discussed and related to recent initiatives to improve both the status of teaching within medical schools and the quality of medical education.

Teachers at a British medical school.

Clinical teachers' attributes, beliefs and attitudes to teaching were measured by mailing a questionnaire to a 50% sample of staff at a British medical school. This paper describes the attributes of the 80% who responded. The majority (83%) were male and females were particularly under-represented in the upper echelons of academia. Most (57%) taught at least once weekly, though 20% taught less often than once a month. The 41% who were primarily NHS employees were as active in teaching as those employed by the University. Small group teaching was most frequently undertaken by 73%, though 17% (who were more likely to be University employees) most often lectured. Only 19% of teachers had attended a course in medical education in the previous 5 years--these were more likely to have qualified relatively recently and to be University employees. Few (9%) teachers claimed membership of a medical education society. It is hoped that these findings will stimulate debate on how medical school teachers are selected, how they can be helped to improve their teaching performance and how their enthusiasm for teaching can be fostered.

Screening for diabetic retinopathy.

There is a need for greater educational emphasis, both at undergraduate and postgraduate level, on the detection of diabetic eye disease, in particular diabetic retinopathy. The early diagnosis of the sight-threatening lesions of proliferative retinopathy and maculopathy is a prerequisite for the prevention or reduction of the visual loss and blindness associated with this diabetic complication. It is also essential that patients are aware that diabetes can result in visual loss due to diabetic retinopathy. Patients should understand that diabetic retinopathy may be present without ophthalmic or diabetic symptoms and that its incidence increases with duration of diabetes, poor diabetes control, and hypertension. They must also be aware that, if detected early, retinopathy can be treated successfully and vision preserved. Early detection depends on regular eye examination involving both visual acuity assessment and ophthalmoscopy through dilated pupils by experienced personnel. A comprehensive programme of screening followed by prompt and adequate treatment would made a significant contribution to eradicating diabetic retinopathy as a cause of blindness.

Continuing education for general practice and the role of the pharmaceutical industry.

A survey of the involvement in and attitudes towards continuing medical education of 101 general practitioners achieved a 95% response rate. Ninety per cent of the 96 doctors worked in practices which held meetings the content of which was organized by representatives of pharmaceutical companies but only 46% worked in practices which organized their own educational meetings. Seventy six per cent attended meetings away from their practice which were organized by drug companies and 75% had attended at some time continuing medical education activities organized by a local postgraduate centre. The promotional aspects of the drug company organized meetings were disliked by a majority of respondents (58%); more of the trainers (62%) and more of those who had entered general practice within the last seven years (71%) disliked this aspect. Nonetheless the educational content of both meetings held in the practice and those held elsewhere was the aspect most liked by over half of the respondents (59% and 53% respectively). Only 16% of all respondents thought that visits by representatives from pharmaceutical companies were educationally valuable and 37% thought that educational events organized by these companies were of value. Surprisingly 60% of those who worked in practices which held meetings organized by drug company representatives thought them to be of little or no educational value. There is clearly a need for practice based continuing medical education but the current level of dependence on drug companies for organizing these meetings must be questioned. Alternative strategies for the provision of independent non-sponsored educational activities should be sought.

Unawareness of hypoglycaemia and inadequate hypoglycaemic counterregulation: no causal relation with diabetic autonomic neuropathy.

OBJECTIVE: To examine the traditional view that unawareness of hypoglycaemia and inadequate hypoglycaemic counterregulation in insulin dependent diabetes mellitus are manifestations of autonomic neuropathy. DESIGN: Perspective assessment of unawareness of hypoglycaemia and detailed assessment of autonomic neuropathy in patients with insulin dependent diabetes according to the adequacy of their hypoglycaemic counterregulation. SETTING: One routine diabetic unit in a university teaching hospital. PATIENTS: 23 Patients aged 21-52 with insulin dependent diabetes mellitus (seven with symptoms suggesting autonomic neuropathy, nine with a serious clinical problem with hypoglycaemia, and seven without symptoms of autonomic neuropathy and without problems with hypoglycaemia) and 10 controls with a similar age distribution, without a personal or family history of diabetes. MAIN OUTCOME MEASURES: Presence of autonomic neuropathy as assessed with a test of the longest sympathetic fibres (acetylcholine sweatspot test), a pupil test, and a battery of seven cardiovascular autonomic function tests; adequacy of hypoglycaemic glucose counterregulation during a 40 mU/kg/h insulin infusion test; history of unawareness of hypoglycaemia; and response of plasma pancreatic polypeptide during hypoglycaemia, which depends on an intact and responding autonomic innervation of the pancreas. RESULTS: There was little evidence of autonomic neuropathy in either the 12 diabetic patients with a history of unawareness of hypoglycaemia or the seven patients with inadequate hypoglycaemic counterregulation. By contrast, in all seven patients with clear evidence of autonomic neuropathy there was no history of unawareness of hypoglycaemia and in six out of seven there was adequate hypoglycaemic counterregulation. Unawareness of hypoglycaemia and inadequate hypoglycaemic counterregulation were significantly associated (p less than 0.01). The response of plasma pancreatic polypeptide in the diabetic patients with adequate counterregulation but without autonomic neuropathy was not significantly different from that of the controls (change in plasma pancreatic polypeptide 226.8 v 414 pmol/l). The patients with autonomic neuropathy had a negligible plasma pancreatic polypeptide response (3.7 pmol/l), but this response was also blunted in the patients with inadequate hypoglycaemic counterregulation (72.4 pmol/l) compared with that of the controls (p less than 0.05). CONCLUSIONS: Unawareness of hypoglycaemia and inadequate glucose counterregulation during hypoglycaemia are related to each other but are not due to autonomic neuropathy. The blunted plasma pancreatic polypeptide responses of the patients with inadequate hypoglycaemic counterregulation may reflect diminished autonomic activity consequent upon reduced responsiveness of a central glucoregulatory centre, rather than classical autonomic neuropathy.

A supplementary infusion of glucose-dependent insulinotropic polypeptide (GIP) with a meal does not significantly improve the beta cell response or glucose tolerance in type 2 diabetes mellitus.

Newly diagnosed, previously untreated patients with type 2 diabetes mellitus (n = 6) were studied on two separate days after overnight fasts. On each day they were given a 500-kcal mixed meal plus an infusion of either porcine glucose-dependent insulinotropic polypeptide (GIP) (0.75 pmol/kg/min) or control solution (CS) from 0 to 30 min in random order. Frequent measurements of plasma glucose, C-peptide, insulin and GIP concentrations were made. Fasting GIP levels were similar on both days. During the meal plus GIP infusion plasma GIP levels increased from a basal value of 7.6 +/- 1.5 pmol/1 to a peak of 88.6 +/- 5.4 pmol/1 at 30 min. Following the meal infusion of CS GIP increased from a fasting level of 10.3 +/- 1.2 pmol/1 to a significantly lower peak of 58.0 +/- 8.3 pmol/1 at 60 min. During the meal plus GIP infusion GIP levels were higher at 10-45 min and at 90 min (P less than 0.05-0.001). Fasting and postprandial glucose, C-peptide and insulin levels were, however, similar on both study day. A supplementary infusion of porcine GIP with a mixed meal did not significantly alter the beta cell response or glucose tolerance in this group of patients with type 2 diabetes mellitus.

The glucose dependent insulinotropic polypeptide response to oral glucose and mixed meals is increased in patients with type 2 (non-insulin-dependent) diabetes mellitus.

Considerable disagreement exists regarding the levels of immunoreactive glucose dependent insulinotropic polypeptide in patients with Type 2 (non-insulin-dependent) diabetes mellitus. Glucose dependent insulinotropic polypeptide levels were therefore studied during oral glucose and mixed meal tolerance tests in normal subjects (n = 31) and newly presenting previously untreated patients with Type 2 diabetes mellitus (n = 68). The tests were performed in random order after overnight fasts and blood samples were taken at 30 min intervals for 4 h. During the oral glucose tolerance test plasma glucose dependent insulinotropic polypeptide levels increased in the normal subjects from a fasting value of 20 +/- 3 pmol/l to a peak of 68 +/- 5 pmol/l at 30 min and in the Type 2 diabetic patients from a similar fasting level of 27 +/- 3 pmol/l to a higher peak value of 104 +/- 6 pmol/l at 30 min (p less than 0.001). Glucose dependent insulinotropic polypeptide levels were significantly higher in the diabetic patients compared with the normal subjects from 30-90 min (p less than 0.01-0.001) following oral glucose. During the meal tolerance test glucose dependent insulinotropic polypeptide levels increased in the normal subjects from a pre-prandial value of 22 +/- 4 pmol/l to a peak of 93 +/- 6 pmol/l at 90 min and in the Type 2 diabetic patients from a similar basal level of 25 +/- 2 pmol/l to a higher peak of 133 +/- 7 pmol/l at 60 min. Glucose dependent insulinotropic polypeptide concentrations were significantly higher in Type 2 diabetic patients compared with the normal subjects at 30 min (p less than 0.001), 60 min (p less than 0.01) and from 210-240 min (p less than 0.05) during the meal tolerance test. The groups were subdivided on the basis of degree of obesity and glucose dependent insulinotropic polypeptide concentrations were still higher in the diabetic subgroups compared with the normal subjects matched for weight. Type 2 diabetes mellitus is associated with an exaggerated glucose dependent insulinotropic polypeptide response to oral glucose and mixed meals which is independent of any effect of obesity.

General practitioners' continuing medical education within and outside their practice.

To study continuing medical education 96 out of 101 general practitioners chosen at random from the list held by a family practitioner committee were interviewed. The results provided little evidence of regular attendance at local postgraduate centre meetings, though practice based educational meetings were common. Thirty one of the general practitioners worked in practices that held one or more practice based educational meetings each month at which the doctors provided the main educational content. Performance review was undertaken in the practices of 51 of the general practitioners, and 80 of the doctors recognised its value. The general practitioners considered that the most valuable educational activities occurred within the practice, the most valued being contact with partners. They asked for increased contact with hospital doctors. The development of general practitioners' continuing medical education should be based on the content of the individual general practitioner's day to day work and entail contact with his or her professional colleagues.

The use of videorecordings of medical postgraduates in improving clinical skills.

The examination for membership of the Royal Colleges of Physicians has a high failure rate despite intensive clinical coaching provided by many postgraduate courses. One of the main difficulties appears to be the failure of candidates to identify specific shortcomings in their clinical behaviour. In this study videorecording was used as a method of self-appraisal enabling the candidate to identify strengths and weaknesses. The evidence from the study suggests that self-appraisal by videorecording should be used as an adjunct to clinical instruction.

Obesity is associated with increased post-prandial GIP levels which are not reduced by dietary restriction and weight loss.

Obesity is characterised by fasting and post-prandial hyperinsulinaemia. One factor which may contribute to this is overactivity of the enteroinsular axis. Glucose tolerance, beta-cell response and GIP profiles were therefore compared during oral glucose (OGTT), mixed meal (MTT) and intravenous glucose tolerance tests (IVGTT) in both lean (IBW less than 120%) and obese (IBW greater than 120%) healthy subjects. The tests were repeated in the obese group after a period of dietary restriction and weight loss. Fasting GIP concentrations were similar, but postprandial levels were significantly greater in the obese subjects during both the OGTT and MTT. Glucose profiles were similar but associated with basal and stimulated hyperinsulinaemia in the obese subjects indicating insulin resistance. GIP levels did not change during the IVGTT and were similar in the two groups throughout the test. Following diet and weight-reduction there was a significant decrease in both fasting and post-prandial insulin levels in the obese subjects but there were no significant changes in glucose or GIP concentrations. In conclusion the endogenously stimulated plasma GIP response is exaggerated in obese healthy subjects but this increased response is not decreased by short term diet and weight loss. The increased GIP concentrations may contribute the observed hyperinsulinaemia in obesity, but its contribution is likely to be small in view of the decrease in insulin concentrations following diet and weight-loss which was independent of any change in GIP.

Glucose dependent insulinotropic polypeptide (GIP) infused intravenously is insulinotropic in the fasting state in type 2 (non-insulin dependent) diabetes mellitus.

The effects of an intravenous infusion of porcine GIP on beta-cell secretion in patients with untreated type 2 diabetes mellitus have been studied. The subjects were studied on two separate days. After a 10 h overnight fast and a further 120 min basal period they were given an intravenous infusion of porcine GIP (2 pmol.kg-1.min-1) or control solution in random order from 120-140 min. Frequent plasma glucose, insulin, C-peptide and GIP measurements were made throughout and the study was continued until 200 min. Plasma glucose levels were similar throughout both tests. During the GIP infusion there was an early significant rise in insulin concentration from 0.058 +/- 0.006 nmol/l to 0.106 +/- 0.007 nmol/l (P less than 0.01) within 6 min of commencing the GIP infusion and insulin levels reached a peak of 0.131 +/- 0.011 nmol/l at 10 min (P less than 0.01). Insulin levels remained significantly elevated during the rest of the GIP infusion (P less than 0.01-0.001) and returned to basal values 20 min post infusion. No change in basal insulin values was seen during the control infusion. C-peptide levels were similarly raised during the GIP infusion and the increase was significant just 4 min after commencing the GIP infusion (P less than 0.05). GIP levels increased from 16 +/- 3 pmol/l prior to the infusion to a peak of 286 +/- 24 pmol/l 20 min later. At 4 min when a significant beta-cell response was observed GIP levels were well within the physiological range.(ABSTRACT TRUNCATED AT 250 WORDS)

Associations of alcohol consumption with plasma high density lipoprotein cholesterol and its major subfractions: the Caerphilly and Speedwell Collaborative Heart Disease Studies.

In surveys of 4860 middle-aged men in Caerphilly (South Wales) and Speedwell (Bristol) alcohol consumption has been related to high density lipoprotein (HDL) cholesterol and its major subfractions, HDL2 and HDL3, measured in a single fasting blood sample. The results confirm that high density lipoprotein cholesterol concentration increases as the amount of alcohol regularly consumed increases. The relationship appears to be linear and is independent of age, smoking habit, body mass index, low density lipoprotein cholesterol and plasma total triglyceride. This rise in HDL cholesterol is not mediated through either HDL2 cholesterol or HDL3 cholesterol alone. Both subclasses increase significantly and by similar amounts with increasing alcohol intake.

Acetylcholine sweatspot test for autonomic denervation.

A test for autonomic denervation based on the local sweat response to 0.1 ml 1% acetylcholine administered intradermally, which depends on an intact local sympathetic supply, is described. Diabetic autonomic neuropathy affects the longest fibres first and thus the test was applied to the feet. After painting a standard site on the dorsum of the foot with iodine and starch, acetylcholine was injected intradermally in the centre. The normal response, visible to the eye, is a uniform distribution of dark spots of iodine discolouration at the sites of sweat production. In diabetic autonomic neuropathy this pattern is lost to a varying degree. In a photographic image magnified x 10, the spots were counted in sixty 2.5 cm squares in a grid centred on the injection site. 50 normal volunteers aged 18-69 were tested. No effect of age or sex was found. Five or more squares with less than 6 spots was the definition of abnormal. 24 diabetic men who complained of impotence were investigated with the sweatspot test, a pupil test, and cardiovascular autonomic function tests. 13 had abnormal sweatspot tests with scores up to sixty squares with less than 6 spots. In keeping with the increased length of the sympathetic fibres to the feet compared with those to the iris, there was a 30% false-negative rate for the pupil test if the sweatspot test is taken as standard. Agreement between the cardiovascular tests and the sweatspot test was seen in only 17 patients. The sweatspot test appears to be a more sensitive indicator of autonomic neuropathy than the commonly used cardiovascular tests.

Non-insulin-dependent diabetic patients (NIDDMs) do not demonstrate the dawn phenomenon at presentation.

A dawn rise of plasma glucose (PG) and/or insulin, the 'dawn phenomenon', has been commonly reported in treated diabetic patients and normal subjects. To evaluate the effect of treatment on this phenomenon in non-insulin-dependent diabetics (NIDDMs), PG, C peptide, immunoreactive insulin (IRI), growth hormone (GH), cortisol, epinephrine, and norepinephrine were measured hourly between 24.00 and 09.00 h in 17 newly diagnosed untreated NIDDMs (group 1). The study was repeated in 11 patients after a year of treatment (group 2). The PG levels did not change significantly at any time from 03.00 to 08.00 h in group 1 but increased continuously from 6.7 +/- 0.5 mmol/l at 04.00 h to 7.8 +/- 0.5 mmol/l at 08.00 h (P less than 0.01) in group 2. IRI and C peptide decreased significantly after 07.00 h in both groups. GH and catecholamine changes were similar in group 1 and group 2. Cortisol levels showed a nadir at 02.00 h and a peak after 07.00 h in both groups. Our results demonstrate no dawn rise of mean PG, IRI and C peptide in newly diagnosed untreated NIDDMs but a significant rise of PG in the early morning period in NIDDMs after a year of treatment with diet alone and diet plus sulphonylureas. Therefore other factors such as treatment and/or duration of the diabetes may play an important role in the pathogenesis of the dawn phenomenon.

The influence of aprotinin on regional absorption of soluble human insulin.

1. The absorption of 6U of soluble human insulin following subcutaneous injection into the anterior abdominal wall, thigh and into the thigh following admixture with aprotinin was assessed in normal subjects. The plasma immunoreactive insulin profiles were determined during a 6 h post injection period in subjects receiving concomitantly somatostatin to suppress endogenous insulin secretion. 2. Subcutaneous injection of human insulin into the anterior abdominal wall compared with the thigh led to significantly higher incremental insulin levels between 30 and 50 min (P less than 0.05) followed by lower values at 240-300 min (P less than 0.05). The absorption of soluble human insulin from a subcutaneous depot is faster from the anterior abdominal wall compared with the thigh associated with a faster clearance from plasma. 3. Injection into the thigh of insulin admixed with aprotinin resulted in higher plasma insulin levels at 10 min (P less than 0.001) and 20 min (P less than 0.05) compared with insulin given alone. Similarly, the insulin level was significantly higher with the admixture between 10 and 20 min (P less than 0.05) compared with insulin into the anterior abdominal wall. 4. Admixture of insulin with aprotinin therefore leads to an acceleration of the early phase of absorption from subcutaneous tissue due to a local hyperaemic effect.