Induction of parkinsonian resting tremor by stimulation of the caudal zona incerta nucleus: a clinical study

INTRODUCTION

We hypothesise that parkinsonian tremor arises when the caudal zona incerta (cZI) and subthalamic nucleus (STN) are deprived of dopamine and become increasingly responsive to motor cortical alpha and beta frequency oscillations. These oscillations are synchronised and amplified through the basal ganglia thalamocortical loop and entrained into the cerebello-thalamocortical loop via the cZI. On receiving potent gamma-aminobutyric acid (GABA)-ergic alpha and beta frequency oscillations in cZI afferents, ventrolateral (VL) thalamocortical neurons become hyperpolarised and rebound burst fire, generating 4-6 Hz tremor oscillations. We test this hypothesis by stimulating the cZI at alpha and beta frequencies using deep brain stimulation (DBS) in non-tremulous parkinsonian patients to see whether a 4-6 Hz tremor can be induced.

METHOD

This study included 11 patients with non-tremulous Parkinson's disease (PD), who had DBS leads implanted in a range of targets, including the cZI, STN, VL nucleus, globus pallidus internus (GPi), centromedian and parafascicular nucleus (CM/Pf), and the pedunculopontine nucleus (PPN). All patients underwent stimulation of active contacts within their respective targets at a standard pulse width, with frequencies ranging from 5 to 80 Hz up to a maximum tolerated voltage. The frequency of the tremor induced in the hands was recorded by accelerometry.

RESULT

Resting tremor in the 4-6 Hz range could be readily induced following stimulation of the cZI and the VL nucleus between 5 and 40 Hz. Tremor was also seen following STN stimulation; however, this was only at high stimulation voltages (>5 volts). No tremor could be induced following CM/Pf, PPN or GPi stimulation.

CONCLUSION

We discuss the implications of these findings and argue that resting tremor in PD is generated in the cortico-ZI-VL-thalamocortical loop rather than in the cortico-basal-ganglia-thalamocortical loop.

Bilateral stimulation of the caudal zona incerta nucleus for tremor control

INTRODUCTION

The ventrolateral (VL) nucleus of the thalamus is the commonly chosen target for deep brain stimulation (DBS) to alleviate tremor. However, it has a poor efficacy in alleviating proximal tremor and patients may develop tolerance to the action component of tremor. We performed bilateral stimulation of the caudal or motor part of the zona incerta nucleus (cZI) to determine its safety and efficacy in alleviating tremor.

METHODS

5 patients with parkinsonian tremor and 13 with a range of tremors (Holmes (HT), cerebellar (CT), essential (ET), multiple sclerosis (MS) and dystonic tremor (DT)) affecting both the proximal and distal body parts underwent MRI guided, bilateral cZI DBS. Tremor was assessed by the Fahn-Tolosa-Marin (FTM) tremor scale at baseline and at a mean follow-up of 12 months.

RESULTS

Resting PD tremor improved by 94.8% and postural tremor by 88.2%. The total tremor score improved by 75.9% in 6 patients with ET. HT improved by 70.2%, proximal CT by 60.4% and proximal MS tremor by 57.2% in the total tremor rating score. In the single patient with DT, there was improvement in both the dystonia and the tremor. Patients required low voltages of high-frequency stimulation and did not develop tolerance to it. Stimulation-related side effects were transient.

CONCLUSION

This prospective study shows that the cZI may be an alternative target for the treatment of tremor with DBS. In contrast to bilateral DBS of the VL nucleus, it improves all components of tremor affecting both the distal and proximal limbs as well as the axial musculature.

GDNF delivery for Parkinson's disease

The mainstays of Parkinson's disease (PD) treatment remain symptomatic, including initial dopamine replacement and subsequent deep brain stimulation, however, neither of these approaches is neuroprotective. Neurotrophic factors - proteins that activate cell signalling pathways regulating neuronal survival, differentiation, growth and regeneration - represent an alternative for treating dopaminergic neurons in PD but are difficult to administer clinically because they do not pass through the blood-brain barrier. Glial cell line-derived neurotrophic factor (GDNF) has potent neurotrophic effects particularly but not exclusively on dopaminergic neurons; in animal models of PD, it has consistently demonstrated both neuroprotective and neuroregenerative effects when provided continuously, either by means of a viral vector or through continuous infusion either into the cerebral ventricles (ICV) or directly into the denervated putamen. This led to a human PD study in which GDNF was administered by monthly bolus intracerebroventricular injections, however, no clinical benefit resulted, probably because of the limited penetration to the target brain areas, and instead significant side effects occurred. In an open-label study of continuous intraputamenal GDNF infusion in five patients (one unilaterally and four bilaterally), we reported excellent tolerance, few side effects and clinical benefit evident within three months of the commencement of treatment. The clinical improvement was sustained and progressive, and by 24-months patients demonstrated a 57 and 63% improvement in their off-medication motor and activities of daily living UPDRS subscores, respectively, with clear benefit in dyskinesias. The benefit was associated with a significant increase in putamenal 18F-dopa uptake on positron emission tomography (PET), and in one patient coming to autopsy after 43 months of unilateral infusion there was evident increased tyrosine hydroxylase immunopositive nerve fibres in the infused putamen. A second open trial in 10 patients using unilateral intraputamenal GDNF infusions has also demonstrated a greater than 30% bilateral benefit in both on- and off-medication scores at 24 weeks. Based on our 6-month results, a randomized controlled clinical trial was conducted to confirm the open-label results, however, GDNF infusion over 6-months did not confer the predetermined level of clinical benefit to patients with PD despite increased 18F-dopa uptake surrounding the catheter tip. It is possible that technical differences between this trial and the positive open label studies contributed to this negative outcome.

Cytomorphologic findings of hemangiopericytoma of the meninges: a case report

Hemangiopericytomas (HPCs) are tumors, constituting 2.5%, of soft tissue neoplasms. Meningeal hemangiopericytomas are rare non meningothelial mesenchymal tumors of the dura. They were classified as angioblastic meningiomas because of their similarity to meningiomas. However, these tumors are now regarded as distinct entities, akin to hemangiopericytoma elsewhere in the body. Few reports have addressed the fine needle aspiration (FNA) cytology of HPC. We present the cytological findings of one such rare case ofprimary meningeal hemangiopericytoma which metastasized to the lymph node. A 47 years male presented with cervical lymphadenopathy of 2 months duration. He was operated twice in the last 4 years and diagnosed atypical meningioma both times. The patient now also had spinal metastasis producing nerve root compression. Aspiration cytology of the node revealed cellular aspirate demonstrating round to oval cells with ample cytoplasm, round nuclei and inconspicuous nuclei. They showed a characteristic ferning out of blood vessels. Occasional mitosis was present. A diagnosis of malignant tumor of vascular origin was offered. Lymph node biopsy showed a characteristic histological picture of hemangiopericytoma described in other soft tissues. The cytology of this tumor is characteristic, but the rarity of the lesion, especially in metastatic sites makes diagnosis difficult unless a high index of suspicion is present. The recognition of the distinct cytological findings makes this possible. The case documents the role of FNA cytology in confirming HPC.

Effects of antihypertensive drug treatments on fracture outcomes: a meta-analysis of observational studies

OBJECTIVE

To quantitatively pool findings from observational studies on the risk of fracture outcomes associated with exposure to five antihypertensive drug classes: angiotensin-converting enzyme (ACE) inhibitors, diuretics (in particular thiazide diuretics), beta-blockers, calcium-channel blockers and alpha-blockers.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Publications listed in the MEDLINE, EMBASE and LILACS databases, the ISI proceedings, and bibliographies of retrieved articles. Sources were searched from the earliest possible dates through December 2005.

REVIEW METHODS

We included case-control and cohort studies presenting relative risks and confidence intervals (CIs) for the association between exposure to antihypertensive agents and fracture outcomes. Data were extracted onto a standardized computer worksheet. Study quality was assessed using a 10-point questionnaire specific to case-control or cohort study design.

RESULTS

Fifty-four studies were identified. Pooled estimates were computed using the software HEpiMA. The pooled relative risk (RR) of any fracture with use of thiazide diuretics was 0.86 (95% CI 0.81-0.92) and 1.14 (95% CI 0.84-1.54) with use of nonthiazide diuretics. There was a statistically significant reduction of any fracture with use of beta-blockers, (RR 0.86, 95% CI 0.70-0.98). The one study with ACE inhibitor data showed protection (RR 0.81, 95% CI 0.73-0.89). No significant associations were found between fractures and exposure to alpha-blockers or calcium-channel blockers.

CONCLUSIONS

Thiazide diuretics and beta-blockers appear to lower the risk of fractures in older adults. However, these agents cannot be recommended as preventive therapies for fractures until data from randomized controlled trials have established their efficacy. Patients who use these inexpensive drugs as treatments for hypertension may also benefit from a reduction in fracture risk.

Oligomerization triggers binding of a Bacillus thuringiensis Cry1Ab pore-forming toxin to aminopeptidase N receptor leading to insertion into membrane microdomains

Bacillus thuringiensis Cry1A toxins, in contrast to other pore-forming toxins, bind two putative receptor molecules, aminopeptidase N (APN) and cadherin-like proteins. Here we show that Cry1Ab toxin binding to these two receptors depends on the toxins' oligomeric structure. Toxin monomeric structure binds to Bt-R1, a cadherin-like protein, that induces proteolytic processing and oligomerization of the toxin (Gomez, I., Sanchez, J., Miranda, R., Bravo A., Soberon, M., FEBS Lett. (2002) 513, 242-246), while the oligomeric structure binds APN, which drives the toxin into the detergent-resistant membrane (DRM) microdomains causing pore formation. Cleavage of APN by phospholipase C prevented the location of Cry1Ab oligomer and Bt-R1 in the DRM microdomains and also attenuates toxin insertion into membranes despite the presence of Bt-R1. Immunoprecipitation experiments demonstrated that initial Cry1Ab toxin binding to Bt-R1 is followed by binding to APN. Also, immunoprecipitation of Cry1Ab toxin-binding proteins using pure oligomeric or monomeric structures showed that APN was more efficiently detected in samples immunoprecipitated with the oligomeric structure, while Bt-R1 was preferentially detected in samples immunoprecipitated with the monomeric Cry1Ab. These data agrees with the 200-fold higher apparent affinity of the oligomer than that of the monomer to an APN enriched protein extract. Our data suggest that the two receptors interact sequentially with different structural species of the toxin leading to its efficient membrane insertion.

MRI directed bilateral stimulation of the subthalamic nucleus in patients with Parkinson's disease

OBJECTIVE

Bilateral chronic high frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) has emerged as an appropriate therapy for patients with advanced Parkinson's disease refractory to medical therapy. Advances in neuroimaging and neurophysiology have led to the development of varied targeting methods for the delivery of this treatment. Intraoperative neurophysiological and clinical monitoring is regarded by many to be mandatory for accurate STN localisation. We have examined efficacy of bilateral STN stimulation using a predominantly magnetic resonance imaging (MRI)-directed technique.

METHODS

DBS leads were stereotactically implanted into the STN using an MRI directed method, with intraoperative macrostimulation used purely for adjustment. The effects of DBS were evaluated in 16 patients followed up to 12 months, and compared with baseline assessments. Assessments were performed in both off and on medication states, and were based on the Unified Parkinson's Disease Rating Scale (UPDRS) and timed motor tests. Functional status outcomes were examined using the PDQ-39 quality of life questionnaire. A battery of psychometric tests was used to assess cognition.

RESULTS

After 12 months, stimulation in the off medication state resulted in significant improvements in Activities of Daily Living and Motor scores (UPDRS parts II and III) by 62% and 61% respectively. Timed motor tests were significantly improved in the off medication state. Motor scores (UPDRS part III) were significantly improved by 40% in the on medication state. Dyskinesias and off duration were significantly reduced and the mean dose of L-dopa equivalents was reduced by half. Psychometric test scores were mostly unchanged or improved. Adverse events were few.

CONCLUSIONS

An MRI directed targeting method for implantation of DBS leads into the STN can be used safely and effectively, and results are comparable with studies using intraoperative microelectrode neurophysiological targeting. In addition, our method was associated with an efficient use of operating time, and without the necessary costs of microelectrode recording.

Expression of an Aedes aegypti cation-chloride cotransporter and its Drosophila homologues

Insects maintain haemolymph homeostasis under different environmental conditions by modulating the concentrations of Na+, K+ and Cl- ions. One group of proteins involved in ion transport across cell membranes consists of cation-chloride cotransporters that form a family of structurally similar proteins. Although much is known about these proteins in mammalian systems, our understanding of them in insects is lacking. The recent sequencing of two insect genomes, Drosophila and Anopheles, enabled us to identify globally members of the family of cation chloride cotransporters in these insects. Using RT-PCR we monitored the transcription of members of this family in development and in several tissues. Our analyses showed that transcription of these genes differ considerably from the ubiquitously and highly expressed CG5594 gene to the almost silent gene CG31547. Comparison of Drosophila CG12773 and its Aedes homologue AaeCG12773 showed that they have similar transcript expression profiles. Immunohistochemical analysis of AaeCG1277 gene expression revealed that it is highly expressed in the gut of larvae and female adults but not in Malpighian tubules. A more detailed analysis showed that this protein is localized predominantly in the basolateral membrane of these tissues. This expression pattern confirmed the results of RT-PCR analysis. We also created a mutant for one of the genes, CG10413, in Drosophila using P-element excision. Analysis of this mutant showed this protein does not appear to be essential for development.

Chronic subdural haematoma and the enigmatic eosinophil

The membranes from 50 cases of chronic subdural haematomas were examined histologically and correlated with the duration of the lesion. Cases were divided into three groups based on duration from time of trauma and/or onset of clinical symptoms to date of surgery - Group I: 1 to 30 days, Group II: 31 to 90 days and Group III: >90 days. Infiltration with eosinophils was observed in the vascularised and hyalinised granulation tissue of the subdural membrane in 30 of the 50 cases (60%). There was a trend to correlation both of the frequency and the extent of eosinophilic infiltration with duration of haematoma. Thus, eosinophils were encountered in about half the cases with duration up to 3 months which increased to 80% in cases with duration more than 3 months. The extent of eosinophilic infiltration (mild, moderate or severe) also appeared to correlate with duration of haematoma in that mild infiltration was more common in Group I cases while moderate to severe infiltration were more frequently observed in Group II and III cases. No correlation was observed of the eosinophilic infiltrate with age and sex of the patients or with presence of other cellular inflammatory components of the membrane. Interestingly, a finding hitherto unreported in English literature was the demonstration of mast cells in 7 of 16 membranes (44%) which had been stained using toluidine blue. It is possible that the eosinophils appear at this unusual site due to chemotactic stimulus abetted by these mast cells as well as lymphocytes and haemosiderin pigment. The eosinophils may have an important role in the repair and healing process of these membranes.

Laminal fenestration for the treatment of lumbar nerve root foraminal stenosis

A new technique is reported for the treatment of isolated lumbar nerve root foraminal stenosis. Nerve root decompression is performed via a 5-mm drill hole in the lamina immediately below the superior facet. This technique preserves spinal stability even if done at multiple levels. It also provides early mobility of the patient and subsequently shortens the hospital stay. The technical details are described.

The influence of preoperative nutritional status in wound healing after replacement arthroplasty

Patient nutritional status was evaluated preoperatively using the serological parameters serum albumin, serum transferrin, and total lymphocyte count in 40 patients who underwent replacement arthroplasty (33 hips and 7 knees). Using the standard criteria, the overall incidence of malnutrition was 40% (16 cases). Ten percent (4 patients) had a negative value in the Rainey McDonald nutritional index. On follow-up, no patient had delayed wound healing or wound infection. Attention to surgeon-dependent factors can offset the high risk of delayed wound healing imposed by patient-dependent factors.

Comparative strength of three methods of fixation of transverse acetabular fractures

With the advent of percutaneously placed lag screws for fixation of acetabular fractures, this study evaluated the strength of lag screw fixation compared with traditional fixation techniques of transverse acetabular fractures. Ten formalin-treated human, cadaveric pelvic specimens with bilateral, transtectal transverse acetabular fractures were used for this study. The right acetabular fractures were fixed with a five-hole plate and four screws with the central hole spanning the posterior fracture site. The left acetabular fractures were fixed with two lag screws, one each in the anterior and posterior columns, or with a screw and wire construct stabilizing both columns. The specimens were loaded to implant failure. Stiffness, yield strength, maximum load at failure, and site of failure was recorded. The plate and screw construct showed significantly greater yield and maximum strength when compared with the two lag screws. The stiffness of the lag screw method was 39% higher than that of the plating method, but this result was not statistically significant. In addition, the plate and screw method provided significantly greater maximum strength than the screw and wire technique. The quadrilateral plate seemed to be the weakest area of fixation because 83% of the implant failures occurred in this region. In patients in whom the risks of formal open reduction and internal fixation of acetabular fractures outweigh the possible benefits, such as in patients with burns or degloved skin, the advent of computer-assisted and fluoroscopically guided percutaneous surgical techniques have been instrumental. This study showed there is greater strength of fixation with a plate and screw construct, possibly secondary to supplementary fixation distal to the quadrilateral plate. However, lag screw fixation provided relatively greater stiffness, which may account for its clinical success. Percutaneous lag screw fixation of appropriate transverse acetabular fractures is a viable option.

Small intestinal neoplasms

Small intestinal neoplasms are uncommonly encountered in clinical practice. They may occur sporadically, in association with genetic diseases (e.g., familial adenomatous polyposis coli or Peutz-Jeghers syndrome), or in association with chronic intestinal inflammatory disorders (e.g., Crohn's disease or celiac sprue). Benign small intestinal tumors (e.g., leiomyoma, lipoma, hamartoma, or desmoid tumor) usually are asymptomatic but may present with intussusception. Primary malignancies of the small intestine-including adenocarcinoma, leiomyosarcoma, carcinoid, and lymphoma-may present with intestinal obstruction, jaundice, bleeding, or pain. Extraintestinal neoplasms may involve the intestine via contiguous spread or peritoneal metastasis. Hematogenous metastases to the intestine from an extraintestinal primary are unusual and are most typical of melanoma. Because the small intestine is relatively inaccessible to routine endoscopy, diagnosis of small intestinal neoplasms is often delayed for months after onset of symptoms. When the diagnosis is suspected, enteroclysis is the most useful imaging study. Small bowel endoscopy (enteroscopy) is increasingly widely available and may permit earlier, nonoperative diagnosis.

Posterior-only unit rod instrumentation and fusion for neuromuscular scoliosis

STUDY DESIGN

A retrospective study to determine the efficacy of posterior-only unit rod instrumentation and fusion in a skeletally immature neuromuscular scoliosis population.

OBJECTIVE

To determine whether the posterior-only approach to this population adequately addresses the concerns of correction of scoliosis and pelvic obliquity, maintenance of that correction over time, and the incidence of crankshaft phenomenon.

SUMMARY OF BACKGROUND DATA

Controversy exists regarding the need for anterior release to improve curve flexibility and the need to obtain an anterior arthrodesis in those skeletally immature patients at risk for crankshafting with continued anterior growth.

METHODS

From 1992 through 1997, 28 consecutive skeletally immature patients with neuromuscular scoliosis underwent posterior-only unit rod instrumentation and fusion for the treatment of progressive, symptomatic spinal deformities. Preoperative, immediate postoperative, and final follow-up radiographs were analyzed with respect to scoliosis and pelvic obliquity correction, maintenance of that correction over time, and the development of the crankshaft phenomenon as evidenced by loss of correction and/or increased rib-vertebral angle difference. The average age of the patients was 12.8 years and the average follow-up was 58 months with a minimum of 2 years.

RESULTS

Twenty-six patients were available for final follow-up. The initial Cobb angle correction averaged 66%, with 75% of the pelvic obliquity corrected. These corrections were maintained over time. Before surgery 27 of 28 patients were Risser 0, 1, or 2. The triradiate cartilage was open in nine patients, and five patients were < or =10 years of age. At the final follow-up 22 of the 26 patients were Risser 5 and 4 were Risser 4. There was one patient with increased rib-vertebral angle difference over the length of follow-up, with no loss of frontal or sagittal plane alignment.

CONCLUSIONS

These results indicate that even in the very young neuromuscular patient, acceptable amounts of curve correction can be achieved and maintained with posterior-only unit rod instrumentation and fusion. The biomechanical stiffness of this construct seemed to be able to prevent the crankshaft phenomenon in the majority of those patients at risk.

Improving prescribing in the elderly: a study in the long term care setting

OBJECTIVES

To determine the prevalence and predictors of potentially inappropriate prescribing of medications in the long term care setting, and to determine the effectiveness of follow-up pharmacist letters to the prescribing physicians in improving prescribing.

PATIENTS AND METHODS

The Improving Prescribing in the Elderly Tool was applied to the charts of all long term care patients aged 65 years and over at Parkwood Hospital, a rehabilitation hospital/long term care facility in London, Ontario. All potentially inappropriate prescriptions were verified by a consensus panel consisting of a family physician, a geriatric medicine specialist and a geriatric pharmacist. Follow-up letters to the prescribing physicians were developed that briefly described the concerns with the potentially inappropriate prescriptions and suggested safer alternatives. These letters were sent to the prescribing physicians, accompanied by a brief survey. Patient charts in which a potentially inappropriate prescription had been noted were reviewed for prescription changes two months after the prescribing physicians had received the follow-up letters.

RESULTS

A total of 69 potentially inappropriate prescriptions were found in 65 of 355 long term care patients (18.3%). The most common types of potentially inappropriate prescriptions were anticholinergic drugs to manage antipsychotic side effects (17 cases), tricyclic antidepressants with active metabolites (16 cases), and long-acting benzodiazepines (14 cases). The total number of prescription medications (P<0.001), a history of mental illness (P=0.002) and a high minimum data set (MDS) score for depression (P=0.002) were all highly associated with potentially inappropriate prescribing. Variables that were not correlated with increased rates of potentially inappropriate prescribing included age, sex, code status, a diagnosis of dementia (as documented explicitly in the chart), high MDS scores for delirium or cognitive impairment, the date of the prescribing physician's graduation and the total Charlson comorbidity index score. Potentially inappropriate prescriptions were significantly less common in patients seen by a geriatric medicine specialist (P<0.001). In response to the follow-up letter suggesting safer alternatives, 37.9% of potentially inappropriate prescriptions were changed by the prescribing physician. Ninety-two per cent of responding physicians rated the follow-up letter as a "somewhat" or "very" helpful method for improving prescribing in elderly patients.

CONCLUSIONS

Potentially inappropriate prescribing in the long term care setting is common and can be improved by the provision of a follow-up letter suggesting safer alternatives.

Mapping the epitope in cadherin-like receptors involved in Bacillus thuringiensis Cry1A toxin interaction using phage display

In susceptible lepidopteran insects, aminopeptidase N and cadherin-like proteins are the putative receptors for Bacillus thuringiensis (Bt) toxins. Using phage display, we identified a key epitope that is involved in toxin-receptor interaction. Three different scFv molecules that bind Cry1Ab toxin were obtained, and these scFv proteins have different amino acid sequences in the complementary determinant region 3 (CDR3). Binding analysis of these scFv molecules to different members of the Cry1A toxin family and to Escherichia coli clones expressing different Cry1A toxin domains showed that the three selected scFv molecules recognized only domain II. Heterologous binding competition of Cry1Ab toxin to midgut membrane vesicles from susceptible Manduca sexta larvae using the selected scFv molecules showed that scFv73 competed with Cry1Ab binding to the receptor. The calculated binding affinities (K(d)) of scFv73 to Cry1Aa, Cry1Ab, and Cry1Ac toxins are in the range of 20-51 nm. Sequence analysis showed this scFv73 molecule has a CDR3 significantly homologous to a region present in the cadherin-like protein from M. sexta (Bt-R(1)), Bombyx mori (Bt-R(175)), and Lymantria dispar. We demonstrated that peptides of 8 amino acids corresponding to the CDR3 from scFv73 or to the corresponding regions of Bt-R(1) or Bt-R(175) are also able to compete with the binding of Cry1Ab and Cry1Aa toxins to the Bt-R(1) or Bt-R(175) receptors. Finally, we showed that synthetic peptides homologous to Bt-R(1) and scFv73 CDR3 and the scFv73 antibody decreased the in vivo toxicity of Cry1Ab to M. sexta larvae. These results show that we have identified the amino acid region of Bt-R(1) and Bt-R(175) involved in Cry1A toxin interaction.

Drosophila RNase H1 is essential for development but not for proliferation

Ribonucleases H (RNases H) recognize and specifically degrade RNA that is bound to complementary DNA and are thought to be involved in DNA replication and transcriptional regulation. Though it was previously shown that bacterial RNases H participate in DNA synthesis, none of the known mutations in RNase H genes in either prokaryotes or lower eukaryotes is lethal. Here, we report the characterization of the first loss-of-function mutation in an RNase H1 gene in a metazoan organism, Drosophila melanogaster. Genetic studies of this mutant showed that this gene is essential for metamorphosis in Drosophila. However, disruption of the RNase H1 gene does not affect proliferation, but probably alters the regulation of gene expression. The lethal phenotype of this mutant also demonstrates that RNase H1 activity in Drosophila cannot be provided by other cellular RNase H activities. Analysis of the developmental and spatial expression profiles of a reporter gene placed under the control of the RNase H1 promoter revealed increased expression in several larval tissues. In salivary glands this increase was shown to be inducible by treatment with ecdysone.

Fractures in transfusion dependent beta thalassemia--an Indian study

AIM OF STUDY

To analyse the incidence of fractures in beta thalassemia patients and to identify causative factors.

METHODS

We examined all cases of transfusion dependent beta thalassemia (TDBT) seen at our institute over a two-year period. The transfusion records, incidence of fractures, cause of fracture and Hb levels were recorded. Radiographs of the involved parts were taken in cases with fractures only.

RESULTS AND CONCLUSIONS

Amongst 105 cases of TDBT assessed, 14 sustained a total of 28 fractures. Seven patients sustained more than one fracture. Two thirds of these fractures were caused by trivial trauma. All fractures, except one, were of the closed type. Radiologically, fractures frequently showed minimal or no displacement. All fractures were successfully treated by closed modalities of treatment. Majority of the fractures healed within normal union time for a given bone. Permanent deformities and gross limb length discrepancies were uncommon. On reviewing the literature, we noted that the incidence of fractures in our series and in the latest reports was lesser than previously reported. We postulate that this is a result of better and earlier control of hemoglobin status by improved transfusion techniques, and earlier recognition of the disease. Difficulties arise due to inadequate blood transfusion facilities in developing countries.

Glutamate receptors in peripheral tissues: current knowledge, future research, and implications for toxicology

We illustrate the specific cellular distribution of different subtypes of glutamate receptors (GluRs) in peripheral neural and non-neural tissues. Some of the noteworthy locations are the heart, kidney, lungs, ovary, testis and endocrine cells. In these tissues the GluRs may be important in mediating cardiorespiratory, endocrine and reproductive functions which include hormone regulation, heart rhythm, blood pressure, circulation and reproduction. Since excitotoxicity of excitatory amino acids (EAAs) in the CNS is intimately associated with the GluRs, the toxic effects may be more generalized than initially assumed. Currently there is not enough evidence to suggest the reassessment of the regulated safety levels for these products in food since little is known on how these receptors work in each of these organs. More research is required to assess the extent that these receptors participate in normal functions and/or in the development of diseases and how they mediate the toxic effects of EAAs. Non-neural GluRs may be involved in normal cellular functions such as excitability and cell to cell communication. This is supported by the wide distribution in plants and animals from invertebrates to primates. The important tasks for the future will be to clarify the multiple biological roles of the GluRs in neural and non-neural tissues and identify the conditions under in which these are up- or down-regulated. Then this could provide new therapeutic strategies to target GluRs outside the CNS.

The transporter-like protein inebriated mediates hyperosmotic stimuli through intracellular signaling

We cloned the inebriated homologue MasIne from Manduca sexta and expressed it in Xenopus laevis oocytes. MasIne is homologous to neurotransmitter transporters but no transport was observed with a number of putative substrates. Oocytes expressing MasIne respond to hyperosmotic stimulation by releasing intracellular Ca(2+), as revealed by activation of the endogenous Ca(2+)-activated Cl(−) current. This Ca(2+) release requires the N-terminal 108 amino acid residues of MasIne and occurs via the inositol trisphosphate pathway. Fusion of the N terminus to the rat gamma-aminobutyric acid transporter (rGAT1) also renders rGAT1 responsive to hyperosmotic stimulation. Immunohistochemical analyses show that MasIne and Drosophila Ine have similar tissue distribution patterns, suggesting functional identity. Inebriated is expressed in tissues and cells actively involved in K(+) transport, which suggests that it may have a role in ion transport, particularly of K(+). We propose that stimulation of MasIne releases intracellular Ca(2+) in native tissues, activating Ca(2+)-dependent K(+) channels, and leading to K(+) transport.

Tuberculous anal sepsis: report of clinical features in 20 cases

INTRODUCTION

Tuberculosis is a neglected cause of anal sepsis, often is not recognized, and therefore is not treated properly.

METHOD

All patients were reviewed who had tuberculous anal sepsis diagnosed by histology reports of fistulectomy specimens or abscess scrapings from January 1990 to April 1999.

RESULTS

Twenty patients (median age, 53 years; 18 males) with anal tuberculous sepsis were identified. They presented with abscesses (n = 2), abscesses and fistulas (n = 6), or fistulas (n = 12). All patients had a long history of anal complaints (3 months to 20 years), for which 15 patients were operated on previously. Nearly all fistulas (17/18) were complex, and secondary tracks or additional complicating features were common, even at first presentation. Eight patients had active concurrent pulmonary tuberculosis, and six showed evidence of previous pulmonary tuberculosis. Six patients had no signs of concurrent or previous tuberculosis elsewhere. Recurrence was observed only in cases where tuberculosis was initially not recognized, and antitubercular treatment therefore was not started.

CONCLUSION

Contrary to views held previously, anal tubercular sepsis seems to have characteristic clinical features. It should be considered in cases of known pulmonary or extrapulmonary tuberculosis or if anal sepsis is persistent, recurrent, or complex in nature.

New approach to cervical flexion deformity in ankylosing spondylitis. Case report

The treatment of cervical fixed flexion deformity in ankylosing spondylitis presents a challenging problem that is traditionally managed by a corrective cervicothoracic osteotomy. The authors report a new approach to this problem that involves performing a two-level osteotomy at the level of maximum spinal curvature, thereby achieving complete anatomical correction in a one-stage procedure. This 48-year-old woman with ankylosing spondylitis presented with a 30-year history of progressive neck deformity that left her unable to see ahead and caused her to experience difficulty eating, drinking, and breathing on exertion. On examination, she exhibited a 90 degrees fixed flexion deformity of the cervical spine, which was maximum at C-4; this was confirmed on imaging studies. A two-level osteotomy was performed at C3-4 and C4-5 around the area of maximum spinal curvature, and the deformity was corrected by extending the head on its axis of rotation through the uncovertebral joints. The spine was stabilized using a Ransford loop. An excellent anatomical position was achieved, as was complete correction of the deformity. A two-level midcervical osteotomy performed at the level of maximum spinal curvature in ankylosing spondylitis enables complete correction of severe fixed flexion deformity in a single procedure. Preservation of the uncovertebral joints allows smooth and safe correction of the deformity about their axis of rotation.

Temporal and spatial expression of the cell-cycle regulator cul-1 in Drosophila and its stimulation by radiation-induced apoptosis

Cul-1 protein is part of the ubiquitin ligase complex that is conserved from yeast to humans. This complex specifically marks cell-cycle regulators for their subsequent destruction. Two null mutations of the cul-1 gene are known, in budding yeast and in nematodes. Although in both these organisms the cul-1 gene executes essentially the same function, the manifestation of its lack-of-function mutations differs considerably. In yeast the mutation causes arrest at the G(1)/S-phase transition, whereas in nematodes excessive cell divisions occur because mutant cells are unable to exit the mitotic cycle. We isolated cul-1 orthologues from two model organisms, Drosophila melanogaster and mouse. We show that the Drosophila full-length cul-1 gene restores the yeast mutant's inability to pass through the G(1)/S-phase transition. We also characterize expression of this gene at the transcript and protein levels during Drosophila development and show that cul-1 gene is maternally supplied as a protein, but not as an RNA transcript. Zygotic transcription of the gene, however, resumes at early stages of embryogenesis. We also found an increase in cul-1 transcription in cultured cells treated with a lethal dose of gamma-irradiation.

Tuberculous osteomyelitis of the cuboid: a report of four cases

Osteoarticular tuberculosis, although rare, has shown a resurgence in recent times, especially in immunocompromised patients. Involvement of the foot is infrequent, and the differential diagnosis is confusing, leading to diagnostic delays. We reviewed four cases of tuberculosis of the cuboid where the infection was limited to the bone without articular involvement. All four cases were adults and diagnostic delays were observed in all. Three of the cases had an osteolytic lesion on radiographs resembling a space-occupying lesion. Magnetic resonance imaging (MRI) or Computed tomography (CT) scans were helpful in three cases, and post-treatment MRI helped in evaluating outcome in one case. Antitubercular chemotherapy was sufficient to cause resolution of the lesion in three cases, while in one case surgical intervention was necessary. Since isolated osteomyelitis is usually seen only in the early stages of the disease process, early diagnosis and appropriate therapy are imperative to get good long-term results. Concomitant extraskeletal lesions are not always seen, nor is the organism cultured in a majority of the cases. Thus a high index of suspicion is mandatory in high-risk groups (immigrants, immunocompromised cases or those with history of contact); clinical and radiologic features, along with histopathologic evidence of granulomatous pathology should be sufficient to initiate therapy.

Evaluation of leukergy test as an indicator of infection in hip joint in children

This new blood test (leukergy) for infection is based on the fact that white cells agglomerate in peripheral blood of patients with inflammatory diseases. We evaluated leukergy in 25 children with proven septic arthritis of hip. It was found to be the efficient and earliest indicator of septic arthritis than the erythrocyte sedimentation rate (ESR), total leucocyte count (TLC), polymorphs and C-reactive protein (CRP). It also correlated well with the clinical severity of infection and the prognosis of disease. Thus leukergy is a simple, rapid and inexpensive slide test which was found as the best indicator profile for the presence of septic arthritis.