Asymptomatic pituitary apoplexy after aortocoronary bypass surgery

Pituitary apoplexy usually presents with acute neuro-ophthalmological complications that require urgent neurosurgical intervention. We present a case of pituitary apoplexy following aortocoronary bypass surgery that was asymptomatic until the patient presented with features of hormonal deficiency three months later. Only one case of pituitary apoplexy has been described in the literature following cardiac surgery that did not require operative intervention. We discuss the aetiology of pituitary apoplexy and the possible mechanisms for such an event after cardiac surgery. Although this is rare, any unusual feature after operation such as lethargy or erectile dysfunction should remind us of hypopituitarism.

Coeliac disease in adults: variations on a theme

In childhood, coeliac disease (gluten enteropathy) tends to show itself with failure to thrive and growth retardation; in adult life with malabsorption syndromes. We report six cases in adults who presented atypically, with features including clotting disorder, hypoglycaemia, weight loss, anaemia and angina pectoris, all of which responded to gluten withdrawal.

Atrial fibrillation in a general hospital: how well are we doing?

Atrial fibrillation (AF) is an important risk factor for ischaemic stroke, and anticoagulation is now indicated in many patients, particularly those with congestive cardiac failure, hypertension, a history of transient ischaemic attacks or embolic stroke. In a retrospective study (and audit), we examined 280 cases of AF (acute, paroxysmal non-sustained and chronic sustained) admitted to a general hospital in the UK. The commonest underlying medical condition was ischaemic heart disease (57%), while the commonest presenting feature was congestive cardiac failure (60%). Pharmacological cardioversion was preferred against electrical cardioversion for reverting to sinus rhythm. Fifty-six patients (20%) received warfarin, 55 patients (20%) were on aspirin, and the remaining 169 (60%) received neither warfarin nor aspirin. More awareness is needed among physicians managing AF particularly in relation to anticoagulation.

Thermal, but not mechanical, nociceptive behavior is altered in the Zucker Diabetic Fatty rat and is independent of glycemic status

This study investigated the possible link between developing hyperglycemia and mechanical and/or thermal hyperalgesia in the Zucker Diabetic Fatty (ZDF) rat. When normoglycemic (nonfasting blood glucose levels of 6 mM), 6-week-old ZDF rats were glucose intolerant compared to the nondiabetic Zucker lean control (ZL) rats, but there was no difference in their response to a noxious mechanical (paw pressure test) or thermal (hot plate) stimulus (mechanical nociceptive thresholds: ZDF 176.7+/-14.4 g, ZL 161.7+/-13.3 g; latencies to response to the thermal stimulus: ZDF 13.1+/-1.6 sec, ZL 16.7+/-1.5 sec). Blood glucose levels in untreated ZDF rats increased to 28.4+/-2.9 mM by 20 weeks of age, while ZDF rats treated with the insulin sensitizer, rosiglitazone, and ZL rats remained normoglycemic (< or =8 mM) throughout the study. Hyperglycaemia in ZDF rats was not associated with mechanical hyperalgesia, as the nociceptive threshold remained constant in both the rosiglitazone-treated and untreated ZDF rats and in the ZL rats throughout the study. In contrast, the latency to response to the thermal stimulus increased with time in ZL rats, but remained constant in hyperglycaemic ZDF rats such that the difference reached significance by 9 weeks of age (ZDF 11.6+/-1.7 sec, ZL 21.8+/-2.7 sec, p<0.01) and is consistent with hyperalgesia in the ZDF phenotype. However, this difference was not moderated by maintaining normoglycaemia in rosiglitazone-treated ZDF rats (12.8+/-1.3 sec). Together, the data suggest that hyperglycemia does not play a central role in the development of hyperalgesia in the ZDF rat.

TrkA glycosylation regulates receptor localization and activity

The human nerve growth factor receptor (TrkA) contains four potential N-glycosylation sites that are highly conserved within the Trk family of neurotrophin receptors, and nine additional sites that are less well conserved. Using a microscale deglycosylation assay, we show here that both conserved and variable N-glycosylation sites are used during maturation of TrkA. Glycosylation at these sites serves two distinct functions. First, glycosylation is necessary to prevent ligand-independent activation of TrkA. Unglycosylated TrkA core protein is phosphorylated even in the absence of ligand stimulation and displays constitutive kinase activity as well as constitutive interaction with the signaling molecules Shc and PLC-gamma. Second, glycosylation is required to localize TrkA to the cell surface, where it can trigger the Ras/Raf/MAP kinase cascade. Using confocal microscopy, we show that unglycosylated active Trk receptors are trapped intracellularly. Furthermore, the unglycosylated active TrkA receptors are unable to activate kinases in the Ras-MAP kinase pathway, MEK and Erk. Consistent with these biochemical observations, unglycosylated TrkA core protein does not promote neuronal differentiation in Trk PC12 cells even at high levels of constitutive catalytic activity.

Diabetic ketoacidosis precipitated by thyrotoxicosis

We report two patients with type 1 diabetes mellitus, previously well controlled with good compliance, presenting with unexplained diabetic ketoacidosis. Following initial correction of the metabolic disorder, persisting tachycardia lead to the diagnosis of thyrotoxicosis. In both cases, treatment with propranolol and carbimazole helped in the stabilization of their metabolic states. Although thyrotoxicosis is known to destabilize diabetes control, we can find no reports of it precipitating diabetic ketoacidosis.

Laser and multipolar electrocoagulation ablation of early Barrett's adenocarcinoma: long-term follow-up

BACKGROUND

Endoscopic ablation of Barrett's esophagus, including associated dysplasia and adenocarcinoma, can be achieved by various techniques, but few long-term results are available. The aim of our study was ablation of intramucosal adenocarcinoma with a combination of Nd:YAG laser plus multipolar electrocoagulation.

METHODS

Patients with documented Barrett's esophagus and adenocarcinoma who either had refused surgery or were poor candidates for surgery because of high risk were offered endoscopic therapy. Patients underwent therapy with Nd:YAG laser and multipolar electrocoagulation. They were treated with omeprazole (20 mg twice daily) as maintenance therapy.

RESULTS

Six patients were enrolled in the study over a 7-year period. All were men with a mean age of 78.2 years. The mean length of Barrett's esophagus was 6.0 cm (range, 3 to 10 cm). Seventeen Nd:YAG laser (mean, 2.8/patient) and 20 multipolar electrocoagulation (mean, 3.3/patient) sessions were used during the study period. All patients had a complete initial response to therapy. One patient on chronic immunosuppressive medications had recurrence of the tumor after an initial complete response (36-month follow-up). Two patients have no evidence of Barrett's esophagus, and 3 patients have residual intestinal metaplasia on biopsy of an irregular appearing "neo" Z-line. Mean follow-up in this group is 3.4 years (range, 9 to 86 months).

CONCLUSIONS

Laser photocoagulation and multipolar electrocoagulation can be successfully and safely used to ablate intramucosal adenocarcinoma in the setting of Barrett's esophagus. Patients remain functional with normal swallowing.

Thyrotoxicosis and abdominal pain: atypical presentation in a middle-aged man

A45-year-old man was referred to the surgical assessment unit by his GP with a 1-week history of vomiting and severe abdominal pain. Marked tenderness was noted in the epigastrium and umbilical region. He was dehydrated with blood pressure 100/70 mmHg and pulse of 110/min. The rest of the initial examination was normal. Abdominal and chest X-ray, electrocardiogram, routine blood tests, including full blood count, liver and kidney functions, cardiac enzymes and serum amylase were normal as were the ultrasound scan of the abdomen and endoscopy of stomach and duodenum. Serum calcium was very high at 3.11 mmol/litre (normal 2.10–2.60) with a normal serum phosphate level.

Treatment with normal saline, frusemide and pamidronate (three daily doses of 30 mg each) reduced the serum calcium to 2.94 mmol/litre with little symptomatic improvement. He also had tremor and a small goitre when thyrotoxicosis was suspected and confirmed (free thyroxine 57.5, normal 9–24 pmol/litre; triiodothyronine 8.9, normal 0.8–2.7 nmol/litre; and undetectable thyroid- stimulating hormone, normal 0.4–4 mu/litre). Serum parathyroid hormone subsequently was reported as low (<5, normal 12–81pg/ml). He was treated with carbimazole 40 mg daily with remarkable improvement. Subsequently alternative causes of hypercalcaemia were excluded by a normal serum and urine electrophoresis, and bone scan. Serum calcium returned to normal in 3 weeks time. He received radioactive iodine, and became hypothyroid 5 months later. He had done well on follow-up with 75 μg thyroxine daily and serum calcium remained normal.

Hypertension in elderly--an overview

Hypertension (HT) is a common disease in elderly. It has different pathophysiologic, clinical and therapeutic implications in this age group. Due to loss of arterial wall elasticity with age, major vessels including aorta become stiff and less distensible. As age advances, these stiff vessels also lose beta adrenergic responsiveness with unchanged alpha adrenergic responsiveness. These together raise peripheral vascular resistance and aortic impedance which needs a powerful systolic ejection of left ventricle to maintain cardiac output. Result is rise in systolic blood pressure (SBP) and increase in left ventricular (LV) mass with compromised cardiac output and renal blood flow. Participation of renin-angiotensin system and kidney in HT pathogenesis in elderly are minimum. Diagnosis of HT in elderly is made if SBP > 140 mm Hg and/or diastolic blood pressure (DBP) > 90 mm Hg or is taking antihypertensive medications. Isolated systolic hypertension (ISH) means SBP > 140 mm Hg with DBP < 90 mm Hg. Measurement of blood pressure (BP) is problematic, mainly due to pseudo HT, postural hypotension and white-coat HT. HT in absence of end organ changes suggest pseudo HT. Postural hypotension must be detected and treated. Systolodiastolic HT, carried over from middle age is the commonest type of HT in elderly. ISH is also common (10%). Atherosclerotic renovascular disease can cause secondary HT. Therapy is always needed in HT in elderly. Chance of coronary artery disease (CAD) and cerebrovascular accident (CVA) are quite high amongst elderly hypertensives. SBP is more dangerous than DBP. Benefits of therapy are more when compared to young. HT should be treated if SBP > 160 mm Hg and/or DBP > 90 mm Hg. ISH needs therapy if SBP > 160 mm Hg. The benefits of therapy becomes less after 80 years. Treatment goal should be to keep BP below 140/90 mm Hg. Therapy should be gradual and stepwise. Na-restriction should be modest. Diuretics (e.g., thiazide 25 mg/day) are the drug of choice unless contra-indicated. Beta blockers are inferior agents compared to diuretics unless angina or acute myocardial infarction (AMI) is present. Angiotensin converting enzyme (ACE) inhibitors are drug of choice only if congestive cardiac failure (CCF) and/or diabetes is present or other drugs are contra-indicated. Calcium entry blockers (CEB) are new but very good alternative to diuretics in elderly. Due to abnormal physiology, pharmacokinetics and drug interactions, side-effects are very common in elderly. They should be detected early and treated.

Thyrotoxicosis in old age: a different clinical entity?

Thyrotoxicosis generally presents with classic signs and symptoms in younger people. Among the elderly population atypical presentation is recognized, although this has not been well quantified or characterized. To avoid misdiagnosis or delay in diagnosis, clinical suspicion needs to remain high.

Autoimmune thrombocytopenic purpura in a splenectomised patient

Splenectomy remains a treatment in patients with autoimmune thrombocytopenic purpura (ATP) who fail to respond adequately to conservative treatment. We report on a 78-year-old man who developed ATP after splenectomy performed six years earlier for iatrogenic injury to the spleen during hemicolectomy. Incidentally, he suffered from colonic and prostatic malignancies. To our knowledge, such a case has not been reported before. We discuss the mechanism of thrombocytopenia in ATP and its association with various malignancies.

Xrcc3 is required for assembly of Rad51 complexes in vivo

Rad51 is a member of a family of eukaryotic proteins related to the bacterial recombinational repair protein RecA. Rad51 protein localizes to multiple subnuclear foci in Chinese hamster ovary cells. Subnuclear Rad51 foci are induced by ionizing radiation or the DNA cross-linking agent cisplatin. Formation of these foci is likely to reflect assembly of a multimeric form of Rad51 that promotes DNA repair. Formation of damage-induced Rad51 foci does not occur in the Chinese hamster ovary cell line irs1SF, which is sensitive to DNA damaging agents. The Rad51 focus formation defect of irs1SF cells is corrected by a construct that encodes the repair protein Xrcc3. Xrcc3 is a human homolog of Rad51 previously isolated by virtue of its ability to correct the radiation sensitivity of irs1SF cells. Changes in the steady state level of Rad51 protein do not account for the irs1SF defect nor do they account for the appearance of foci following DNA damage. These results suggest that Xrcc3 is required for the assembly or stabilization of a multimeric form of Rad51 during DNA repair. Cell lines defective in two different components of DNA protein kinase formed Rad51 foci in response to damage, indicating DNA protein kinase is not required for damaged-induced mobilization of Rad51.

Methylene blue staining for intestinal metaplasia of the gastric cardia with follow-up for dysplasia

BACKGROUND

Previous studies by our group have identified a 23% prevalence of intestinal metaplasia involving the gastric cardia in patients undergoing elective esophagogastroduodenoscopy (EGD). The current study evaluates the potential clinical utility of vital staining with methylene blue for detecting intestinal metaplasia of the cardia. In addition, the prevalence of Helicobacter pylori infection and incidence of dysplasia in cardia intestinal metaplasia was assessed.

METHODS

Twenty-four of 104 patients undergoing elective EGD were previously identified with cardia intestinal metaplasia. Twenty-one of these 24 returned for follow-up EGD with methylene blue staining and cardia biopsies. During EGD four random biopsies were taken in the cardia. After staining with methylene blue, four targeted biopsy specimens were taken from any stained areas. H. pylori infection was assessed by rapid urease testing and serologic evaluation.

RESULTS

Staining with methylene blue was positive in 16, equivocal in 4, and negative in 1. Overall, cardia intestinal metaplasia was identified in 17 of 21 patients (81%) by at least one of the 8 biopsies. The sensitivity of detecting intestinal metaplasia by targeted biopsies to stained areas was 67% as opposed to 38% for random biopsies (odds ratio 3.0: 95% CI [0.88,10.24]). The prevalence of H. pylori infection in patients with cardia intestinal metaplasia was 76%. One patient developed low-grade dysplasia, whereas the others remained negative.

CONCLUSIONS

Intestinal metaplasia of the gastric cardia is associated with a high prevalence of H. pylori infection and is a reproducible finding in the majority of patients. Methylene blue staining and an increasing number of biopsies improve the sensitivity of detecting this potentially neoplastic lesion.

The telomere and telomerase: how do they interact?

The tandemly repeated DNA sequence of telomeres is typically specified by the ribonucleoprotein enzyme telomerase. Telomerase copies part of its intrinsic RNA moiety to make one strand of the telomeric repeat DNA. Recent work has led to the concept of a telomere homeostasis system. We have been studying two key physical components of this system: the telomere itself and telomerase. Mutating the template sequence of telomerase RNA caused various phenotypes: (1) mutating specific residues in the ciliate Tetrahymena and two yeasts showed that they are required for critical aspects of telomerase action; (2) certain mutated telomeric sequences caused a previously unreported phenotype, i.e. a strong anaphase block in Tetrahymena micronuclei; and (3) certain template mutations in the telomerase RNA gene of the yeast Kluyveromyces lactis led to unregulated telomere elongation, which in some cases was directly related to loss of binding to K. lactis Rap1p. Using K. lactis carrying alterations in the genes for Rap1p and other silencing components, we proposed a general model for telomere length homeostasis: namely, that the structure and DNA length of the DNA-protein complex that comprises the telomere are key determinants of telomerase access, and hence the frequency of action of telomerase, at the telomere.

A fluorescence spectroscopic and molecular dynamics study of bis-ANS/protein interaction

Despite emergence of bis-ANS as a major fluorescence probe of proteins structure, conformational and spectroscopic properties of protein/bis-ANS complexes remains largely unexplored. We have shown that fluorescence polarization of both ANS and bis-ANS is excitation wavelength dependent and this is a property of all protein-ANS/bis-ANS complexes studied. Bis-ANS excitation maximum is always more red shifted than the corresponding ANS complex. Even when corrected for the red shift, the bis-ANS complexes in some, but not all, cases show only a little lowering of polarization, suggesting modest additional depolarization in bis-ANS compared to ANS. Calculation of energy migration rate between the two rings suggests that energy migration rate should be high at all values of the naphthyl-naphthyl dihedral angle. Although, Molecular mechanics and dynamics calculations show that the lowest energy conformation of bis-ANS is when the two naphthalene rings are roughly perpendicular to each other, due to rapid energy migration this conformation should lead to dramatic lowering of emission anisotropy, unlike what is observed. Salt and temperature dependence of bis-ANS/protein interaction suggests little ionic interaction and pre-dominant interaction through hydrophobic aromatic rings. We conclude that bis-ANS binds to proteins through interaction with the aromatic rings and with two rings nearly parallel to each other.

A cognate tRNA specific conformational change in glutaminyl-tRNA synthetase and its implication for specificity

Conformational changes that occur upon substrate binding are known to play crucial roles in the recognition and specific aminoacylation of cognate tRNA by glutaminyl-tRNA synthetase. In a previous study we had shown that glutaminyl-tRNA synthetase labeled selectively in a nonessential sulfhydryl residue by an environment sensitive probe, acrylodan, monitors many of the conformational changes that occur upon substrate binding. In this article we have shown that the conformational change that occurs upon tRNA(Gln) binding to glnRS/ATP complex is absent in a noncognate tRNA tRNA(Glu)-glnRS/ATP complex. CD spectroscopy indicates that this cognate tRNA(Gln)-induced conformational change may involve only a small change in secondary structure. The Van't Hoff plot of cognate and noncognate tRNA binding in the presence of ATP is similar, suggesting similar modes of interaction. It was concluded that the cognate tRNA induces a local conformational change in the synthetase that may be one of the critical elements that causes enhanced aminoacylation of the cognate tRNA over the noncognate ones.

Squamous islands in Barrett's esophagus: what lies underneath?

OBJECTIVE

Squamous islands are frequently visualized at the time of upper endoscopy in patients with Barrett's esophagus, especially those on proton pump inhibitor therapy (PPI). The significance of these islands is not clearly understood. The aim of this study was to systematically biopsy macroscopic squamous islands and to examine their histologic characteristics.

METHODS

Patients with Barrett's esophagus undergoing surveillance had squamous islands documented and biopsied at the time of endoscopy. Barrett's esophagus was defined as the presence of a columnar lined esophagus on endoscopy with intestinal metaplasia on biopsy. All biopsies were obtained by a single senior endoscopist and were stained with alcian blue at pH 2.5. Biopsy samples with inadequate tissue quantity were not included in the study.

RESULTS

A total of 39 biopsies were obtained from 22 patients. Twenty of the 22 patients were male, with a mean age of 65.4 yr (range 47-80 yr). The mean length of Barrett's mucosa was 5.6 cm (range 1-11 cm). Eleven of 22 patients were on omeprazole (mean dose 29.1 mg/day), whereas seven patients were on lansoprazole (60 mg/day). The mean duration of PPI therapy was 2.3 yr (range 9-71 months) at the time of biopsy of the squamous islands. Three patients were on H2-blocker therapy whereas the remaining patient had not been started on acid suppression therapy. On histology, 24 biopsy specimens (61.5%) revealed only squamous epithelium, whereas 15 (38.5%) showed the presence of intestinal metaplasia underlying the squamous epithelium. There was no significant difference between the patients with and without underlying intestinal metaplasia in regard to age, Barrett's length, dose, and duration of PPI therapy.

CONCLUSION

In more than one-third of biopsies of macroscopic squamous islands within Barrett's esophagus, microscopic intestinal metaplasia is detected. The presence of squamous islands should not be equated with regression of Barrett's esophagus or with decreased cancer risk.

A risk based methodology for assessing the efficacy and priorities for the control of various radiation sources

There is increasing concern as to whether our limited radiation protection resources are being directed to those radiation sources that produce the greatest return as measured by the cost/risk avoided. Major contributors to this problem include public perception and the lack of an accepted methodology for assigning priorities. Described in this report is a new methodology for assigning these priorities on the basis of cost per risk avoided. This methodology provides several different approaches for comparing the cost effectiveness and priority of these sources, as well as insight into the efficacy of regulatory programs. To demonstrate its application, various radiation sources, selected on the basis of providing insight into problem areas, are evaluated and compared. These resulting assessments show that the current funding and prioritization for the control of radiation sources are, in general, exactly opposite to the risk based efficacy for their control. It is hopeful that the insights resulting from these assessments will assist decision-makers in correcting this situation.

Metabolic Study of Isoproturon in Goats Following a Single Oral Administration: Toxicokinetics and Recovery

Toxicokinetic behavior and recoveries of isoproturon from feces, urine, and different tissues of goat were determined after 4, 5, 6, and 7 days following single oral administration at 500 mg/kg. Isoproturon was rapidly absorbed and attained blood concentration within 15 min of administration. The kinetic behavior followed a two-compartment open model. The higher t(1/2)(beta) (9.78 +/- 0.33 h) and V(d)()area (4.49 +/- 0.41 L/kg) associated with lower Cl(B) (0.32 +/- 0.02 L/kg/h) suggested slow elimination from the blood. Approximately 56% of the total administered compound was recovered from feces. The rate of excretion of isoproturon through feces was maximum at 48 h and could not be detected beyond 120 h. The excretion pattern of isoproturon through urine resembled that of feces, and approximately 10-11% was eliminated in urine. A maximum quantity of residue was detected in all tissues of goats slaughtered after 4 days followed by a substantial decline after day 5, and nothing could be detected after day 7. Histopathological study revealed that isoproturon produced moderate cellular changes like fatty degeneration in the liver and kidney and emphysema in the lung after 7 days post administration.