Antiresorptive and anti-angiogenic drug therapy in the pediatric population with reference to medication-related osteonecrosis of the jaw

The objective of this study was to identify the prevalence of osteonecrosis of the jaw in a pediatric population with systemic therapeutic exposure to an antiresorptive, anti-angiogenic, and/or immunomodulating drug (ARAID), and in particular in the subgroup of patients who had undergone invasive dental treatment. This was a retrospective cohort study performed at a single center. The investigation included pediatric patients who had undergone systemic therapy with ARAIDs and who began receiving ARAID therapy at ≤16 years of age. The study included 482 patients who received ARAIDs between January 2011 and January 2021. The most common medication class was bisphosphonates (45.0%), followed by mTOR inhibitors (30.1%) and anti-angiogenics (17.8%). No diagnosis of osteonecrosis of the jaw was observed. From this population, 26 patients were noted to have undergone invasive dental treatment. The duration from treatment to the invasive procedure ranged from 0 to 5.9 years. Medication-related osteonecrosis of the jaw is extremely rare among the pediatric population - much less common when compared to the adult population. Prospective cohort studies and continued evaluation will help determine the incidence and prevalence of medication-related osteonecrosis of the jaw in pediatric patients.

Identification of microbial agents in culture-negative brain abscess samples by 16S/18S rRNA gene PCR and sequencing

Despite clinical suspicion of an infection, brain abscess samples are often culture-negative in routine microbiological testing. Direct PCR of such samples enables the identification of microbes that may be fastidious, non-viable, or unculturable. Brain abscess samples (n = 217) from neurosurgical patients were subjected to broad range 16S rRNA gene PCR and sequencing for bacteria. All these samples and seven formalin-fixed paraffin-embedded tissue (FFPE) samples were subjected to species-specific 18S rRNA PCR for neurotropic free-living amoeba that harbour pathogenic bacteria. The concordance between smear and/or culture and PCR was 69%. One-third of the samples were smear- and culture-negative for bacterial agents. However, 88% of these culture-negative samples showed the presence of bacterial 16S rRNA by PCR. Sanger sequencing of 27 selected samples showed anaerobic/fastidious gram negative bacteria (GNB, 38%), facultative Streptococci (35%), and aerobic GNB (27%). Targeted metagenomics sequencing of three samples showed multiple bacterial species, including anaerobic and non-culturable bacteria. One FFPE tissue revealed the presence of Acanthamoeba 18S rRNA. None of the frozen brain abscess samples tested was positive for 18S rRNA of Acanthamoeba or Balamuthia mandrillaris. The microbial 16/18S rRNA PCR and sequencing outperformed culture in detecting anaerobes, facultative Streptococci and FLA in brain abscess samples. Genetic analyses of 16S/18S sequences, either through Sanger or metagenomic sequencing, will be an essential diagnostic technology to be included for diagnosing culture-negative brain abscess samples. Characterizing the microbiome of culture-negative brain abscess samples by molecular methods could enable detection and/or treatment of the source of infection.

Determination of Collimator Helmet Factors for Leksell Gamma Knife 4C Unit Using GAF Chromic EBT3 Film and ImageJ Software

Background:

Measurement of Collimator helmet factors (CHF) is an important quality assurance procedure to be performed on Leksell Gamma Knife unit at regular interval to make sure that the interchangeable collimator helmet fit into the source channels without any positional inaccuracy which leads to major treatment error. The primary aim of this study is to measure the CHFs for Elekta Leksell Gamma knife 4C helmets using GafChromic EBT3 film and Image J software.

Methods:

GafChromic EBT3 film, EPSON expression 10000 XL scanner and Image J analysis software was used for this study. The calibration curve of GafChromic EBT3 film was generated with known dose values for 14 mm collimator helmet using ImageJ software. The collimator helmet factor (CHF) for 4mm, 8mm and 14 mm collimator helmets were measured by normalizing dose rates of 4mm, 8mm and 14 mm to the dose rate of 18 mm collimator helmet using the previously generated calibration curve. The measured CHF was compared to Elekta reference value and previously published mean values.

Results:

The measured CHFs were 0.896, 0.958, and 0.986 for 4mm, 8mm and 14mm collimators respectively. The percentage difference obtained was 1.7 %, 0.21 %, 0.1 % between measured values and reference values.

Conclusion:

The measurement of CHFs in LGK 4C unit using GafChromic EBT3 film and ImageJ software is a reliable method to verify the manufacturer quoted CHFs in routine quality assurance procedures.

Effects of Heat Exposure from Live-Burn Fire Training on Postural Stability of Firefighters

Firefighters perform physically intensive jobs in suboptimal environments, making it even more important for them to maintain good functional postural balance or stability. As part of their training, firefighters are required to perform physically demanding tasks under high stress and high heat environments. These demanding tasks lead to increased physical fatigue which can then result in poor performance and/or postural instability. The objectives of this study were to 1) investigate the effect of live-firefighting training-induced heat stress on static postural balance, and 2) investigate the association between commonly monitored physiological responses (core body temperature, heart rate, oxygen saturation and blood pressure) and measures of static postural balance. Twenty-six firefighters (mean ± SD: age 36.0 years ±5.2, weight 216 lbs. ± 34, BMI 29.7 ± 4.2) participated in live firefighting training while performing following tasks: search and rescue, hose advancement, and backup. Prior to heat exposure (PRE) and following each scenario (POST1, POST2, POST3), firefighters' postural balance was assessed with a wearable 3-D inertial sensor system quantifying time dependent changes in linear acceleration (LIN ACC) and angular velocity (AV) about three orthogonal axes [Anterior-Posterior (AP), Medial-Lateral (ML), and vertical (V)] during one foot balance tests for 30 seconds under eyes open and eyes closed conditions. The outcome variables from 3-D wearable sensors were used to create 3-D Phase-Plane based postural stability metrics. Physiological measurement of core body temperature (CBT) (measured with a radio pill) as well as perception of heat increased significantly during the live fire-training exercise. In addition, firefighters also perceived an increase in physical fatigue and respiratory distress. Angular combined stability parameters (ACSP), RMS angular velocity around ML axis were significantly correlated with CBT. In the multivariate analysis adjusted for the scenarios, height and weight of the firefighters, these measures of static postural balance were significantly associated with CBT. As per the model results, static postural balance, as indicated by ACSP, worsened with an increase in CBT. Future studies should place sensors at body extremities along with close to center of mass to capture the kinematic movements more comprehensively influencing postural balance.

Sub-lobar dysplasia - A comprehensive evaluation with neuroimaging, magnetoencephalography and histopathology

Sublobar dysplasia, a rare cortical malformation has been defined in only 8 patients to date. It was identified on the basis of histopathological features and MRI findings. We report a right temporal sublobar dysplasia, with detailed evaluation including neuroimaging, magnetoencephalography and histopathology to further characterize the pathology. Additional pathological features included a deep collateral sulcus in the basal right temporal lobe, thinned out right corticospinal tract, and bilateral asymmetric basal ganglia changes. Magnetoencephalograpy localized the seizure focus to the posterior margin of the dysplasia. Histopathological evaluation helped exclude other types of dysplasia. Similar to a previous study, the child had Engel 1a outcome.

Giant Hypothalamic Hamartoma in an Infant: A Case Report and Review of the Literature

Giant hypothalamic hamartomas (GHH) are extremely rare lesions in infants and usually intrinsically epileptogenic. We present the case of a 10-month-old girl child presenting with drug-resistant seizures and a giant hypothalamic lesion that was confirmed as hamartoma on histopathology. Surgical decompression and disconnection from the hypothalamus was performed with the intent of controlling her seizures. Unfortunately, the patient developed right middle cerebral artery and posterior cerebral artery territory infarction, possibly due to vasospasm or thrombosis of the vessels. The patient had a stormy postoperative course but has recovered well neurologically at the 18-month follow-up. Histopathological examination revealed abnormal clusters of NeuN-positive neurons, which was confirmatory of hypothalamic hamartoma. A review of the published literature on infantile GHH, its management and the postoperative complications is undertaken in this short report.

Intrinsic brainstem schwannoma - A rare clinical entity and a histological enigma

Intraparenchymal schwannomas arising in the brainstem are very rare, and only eight cases have been reported in literature till now. We report an intraparenchymal brainstem schwannoma presenting with the classical clinical presentation of an intrinsic brainstem lesion, and discuss its clinicoradiological characteristics and histological origins. We highlight the importance of an intraoperative frozen section diagnosis in such cases. Intraoperative tissue diagnosis significantly may alter the surgical strategy, which should be aimed at near total intracapsular decompression of the schwannoma.

Apoplectic presentation of a cauda equina paraganglioma

Background:

Cauda equina paragangliomas (CEPs) are rare spinal tumors that are mostly misdiagnosed preoperatively as ependymomas or schwannomas on magnetic resonance imaging (MRI). Clinically, they usually present with the gradual onset of back pain and radiculopathy rather than an acute cauda equina syndrome.

Case Description:

A 36-year-old female presented with an acute flaccid paraparesis/cauda equina syndrome. Based upon MRI studies, the predominant differential diagnoses included ependymoma or schwannoma. The intraoperative findings revealed an acute intralesional hemorrhage or apoplexy, responsible for the acute clinical deterioration. Histopathology and immunohistochemistry (IHC) revealed that the tumor was a paraganglioma.

Conclusion:

CEPs commonly present with mild symptoms and signs rather than the acute-onset of a flaccid paraparesis/cauda equina syndrome as seen in this case. Here, the authors review the radiological and histopathological characteristics of CEP and emphasize the role of IHC in differentiating “CEP” from the more common ependymomas.

The Relevance of Interictal Bold Changes to Lateralize Seizure Focus Using Simultaneous EEG-fMRI

Background and Purpose:

The main challenge in assessing patients with epilepsy is the localization of neuronal networks involved in seizure generation and the lateralization of seizure onset. Electro encephalogram-functional magnetic resonance imaging (EEG-fMRI) is a noninvasive multimodal imaging technique for epilepsies where the data is acquired based on the interictal epileptiform discharges (IED). Since this is a new technique, the specificity for lateralizing epileptic focus is yet to be established. The peak blood oxygen level dependent (BOLD) signal in an interictal recording is known to correlate with seizure onset focus. In this study we are proposing a simple and practical method without the need for high end post processing techniques of fmri data. The peak BOLD signal derived from EEG-fMRI aids to lateralise seizure focus in a given cerebral lobe (region of interest, ROI). This is a very useful tool in a clinical setting on a given individual clinical case, when other modalities may be conflicting or inconclusive.

Methods:

We analyzed simultaneous EEG-fMRI of 10 different types of refractory epilepsy. The lateralization index was calculated from the statistical significant clusters obtained between the different ROI and results were validated with other modalities.

Results:

Lateralization of seizure focus corroborated well in temporal and extratemporal lobe epilepsy, reflex epilepsy and lesional epilepsy. The only drawback of EEG-fMRI in our study was if insignificant BOLD changes were associated with the given IED.

Conclusions:

EEG-fMRI can be helpful additional tool in the pre-surgical work-up of refractory epilepsy particularly when lateralization with other modalities is conflicting or inconclusive.

Analysis of Personal and Home Characteristics Associated with the Elemental Composition of PM2.5 in Indoor, Outdoor, and Personal Air in the RIOPA Study

The complex mixture of chemicals and elements that constitute particulate matter (PM*) varies by season and geographic location because source contributors differ over time and place. The composition of PM having an aerodynamic diameter < 2.5 μm (PM2.5) is hypothesized to be responsible, in part, for its toxicity. Epidemiologic studies have identified specific components and sources of PM2.5 that are associated with adverse health outcomes. The majority of these studies use measures of outdoor concentrations obtained from one or a few central monitoring sites as a surrogate for measures of personal exposure. Personal PM2.5 (and its elemental composition), however, may be different from the PM2.5 measured at stationary outdoor sites. The objectives of this study were (1) to describe the relationships between the concentrations of various elements in indoor, outdoor, and personal PM2.5 samples, (2) to identify groups of individuals with similar exposures to mixtures of elements in personal PM2.5 and to examine personal and home characteristics of these groups, and (3) to evaluate whether concentrations of elements from outdoor PM2.5 samples are appropriate surrogates for personal exposure to PM2.5 and its elements and whether indoor PM2.5 concentrations and information about home characteristics improve the prediction of personal exposure. The objectives of the study were addressed using data collected as part of the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study. The RIOPA study has previously measured the mass concentrations of PM2.5 and its elemental constituents during 48-hour concurrent indoor, outdoor (directly outside the home), and personal samplings in three urban areas (Los Angeles, California; Houston, Texas; and Elizabeth, New Jersey). The resulting data and information about personal and home characteristics (including air-conditioning use, nearby emission sources, time spent indoors, census-tract geography, air-exchange rates, and other information) for each RIOPA participant were downloaded from the RIOPA study database. We performed three sets of analyses to address the study aims. First, we conducted descriptive analyses to describe the relationships between elemental concentrations in the concurrently gathered indoor, outdoor, and personal air samples. We assessed the correlation between personal exposure and indoor concentrations as well as personal exposure and outdoor concentrations of each element and calculated ratios between them. In addition, we performed principal component analysis (PCA) and calculated principal component scores (PCSs) to examine the heterogeneity of the elemental composition and then tested whether the mixture of elements in indoor, outdoor, and personal PM2.5 was significantly different within each study site and across study sites. Secondly, we performed model-based clustering analysis to group RIOPA participants with similar exposures to mixtures of elements in personal PM2.5. We examined the association between cluster membership and the concentrations of elements in indoor and outdoor PM2.5 samples and personal and home characteristics. Finally, we developed a series of linear regression models and random forest models to examine the association between personal exposure to elements in PM2.5 and (1) outdoor measurements, (2) outdoor and indoor measurements, and (3) outdoor and indoor measurements and home characteristics. As we developed each model, the improvement in prediction of personal exposure when including additional information was assessed. Personal exposures to PM2.5 and to most elements were significantly correlated with both indoor and outdoor concentrations, although concentrations in personal samples frequently exceeded those of indoor and outdoor samples. In general, for most PM2.5 elements indoor concentrations were more highly correlated with personal exposure than were outdoor concentrations. PCA showed that the mixture of elements in indoor, outdoor, and personal PM2.5 varied significantly across sample types within each study site and also across study sites within each sample type. Using model-based clustering, we identified seven clusters of RIOPA participants whose personal PM2.5 samples had similar patterns of elemental composition. Using this approach, subsets of RIOPA participants were identified whose personal exposures to PM2.5 (and its elements) were significantly higher than their indoor and outdoor concentrations (and vice versa). The results of linear and random forest regression models were consistent with our correlation analyses and demonstrated that (1) indoor concentrations were more significantly associated with personal exposure than were outdoor concentrations and (2) participant reports of time spent at their home significantly modified many of the associations between indoor and personal concentrations. In linear regression models, the inclusion of indoor concentrations significantly improved the prediction of personal exposures to Ba, Ca, Cl, Cu, K, Sn, Sr, V, and Zn compared with the use of outdoor elemental concentrations alone. Including additional information on personal and home characteristics improved the prediction for only one element, Pb. Our results support the use of outdoor monitoring sites as surrogates of personal exposure for a limited number of individual elements associated with long-range transport and with a few local or indoor sources. Based on our PCA and clustering analyses, we concluded that the overall elemental composition of PM2.5 obtained at outdoor monitoring sites may not accurately represent the elemental composition of personal PM2.5. Although the data used in these analyses compared outdoor PM2.5 composition collected at the home with indoor and personal samples, our results imply that studies examining the complete elemental composition of PM2.5 should be cautious about using data from central outdoor monitoring sites because of the potential for exposure misclassification. The inclusion of personal and home characteristics only marginally improved the prediction of personal exposure for a small number of elements in PM2.5. We concluded that the additional cost and burden of indoor and personal sampling may be justified for studies examining elements because neither outdoor monitoring nor questionnaire data on home and personal characteristics were able to represent adequately the overall elemental composition of personal PM2.5.

Predictors of spontaneous transient seizure remission in patients of medically refractory epilepsy due to mesial temporal sclerosis (MTS)

PURPOSE

To analyze the predictors of spontaneous transient seizure remission for ≥1 year in patients with drug-resistant epilepsy (DRE) due to mesial temporal sclerosis (MTS).

METHODS

This analysis included 38 patients with DRE (M:F = 20:18, age: 31.7 ± 10.9 years) diagnosed with unilateral MTS (right:left = 16:22). Group I ('remission' group) comprised of patients with seizure remission (M:F = 10:8, age: 32.8 ± 12.3 years, mean seizure free period: 2.2 ± 1.1 years; median: 2.1 years). Group II ('non-remission' group) comprised of age and gender matched 20 patients (M:F = 10:10, age: 30.7 ± 9.7 years) with unilateral MTS who never had seizure remission and subsequently underwent epilepsy surgery. Groups I and II were compared to find the predictors associated with transient seizure remission.

RESULTS

The age at onset of seizures in group I was 13.2 ± 11.8 years and in group II was 12.0 ± 7.6 years. The duration of seizure was: group I - 19.7 ± 12.5 years and group II - 19.3 ± 7.7 years. Past history of seizure remissions (p < 0.001), frequent periods of remissions (p < 0.001), first remission within a year of onset of seizures (p = 0.04) and normal EEG (p = 0.04) were the important clinical predictors associated with seizure remission in this cohort. Fifteen patients in group I (83.3%) experienced remission following either change in AED (p ≤ 0.001) or increase in AED dosages (p < 0.001). There was no difference between the two groups regarding the type of semiology (partial vs. secondarily generalized) (p = 0.50), family history of seizures (p = 1.0), side of the lesion (p = 0.34), history of febrile seizures (p = 1.0) and the number of AEDs used (p = 0.53).

CONCLUSION

The present study unfolds, some of the clinically relevant predictors associated with transient seizure remission in patients with DRE and MTS. Future molecular and network studies are required to understand its mechanism.

Evolving strategies in mechanobiology to more effectively treat damaged musculoskeletal tissues

In this paper, we had four primary objectives. (1) We reviewed a brief history of the Lissner award and the individual for whom it is named, H.R. Lissner. We examined the type (musculoskeletal, cardiovascular, and other) and scale (organism to molecular) of research performed by prior Lissner awardees using a hierarchical paradigm adopted at the 2007 Biomechanics Summit of the US National Committee on Biomechanics. (2) We compared the research conducted by the Lissner award winners working in the musculoskeletal (MS) field with the evolution of our MS research and showed similar trends in scale over the past 35 years. (3) We discussed our evolving mechanobiology strategies for treating musculoskeletal injuries by accounting for clinical, biomechanical, and biological considerations. These strategies included studies to determine the function of the anterior cruciate ligament and its graft replacements as well as novel methods to enhance soft tissue healing using tissue engineering, functional tissue engineering, and, more recently, fundamental tissue engineering approaches. (4) We concluded with thoughts about future directions, suggesting grand challenges still facing bioengineers as well as the immense opportunities for young investigators working in musculoskeletal research. Hopefully, these retrospective and prospective analyses will be useful as the ASME Bioengineering Division charts future research directions.

Economic recession and headache-related hospital admissions

Incidence of headaches across different regions and its relationship to unemployment rates in the United States before and during an economic recession was evaluated. Years 2008 and 2009 were determined as recessionary period. Headache-related admissions, particularly the uncomplicated headaches, increased significantly during recession. Proportion of women with headaches has increased and the age group of 25-54 years was the most affected during the recession. The hospital charges have increased even though the average length and charge of stay decreased. These findings are consistent with our understanding of effects of stress and unemployment on psychological and physical health.

Melanin content and MC1R function independently affect UVR-induced DNA damage in cultured human melanocytes

Malignant transformation of melanocytes leads to melanoma, the most fatal form of skin cancer. Ultraviolet radiation (UVR)-induced DNA photoproducts play an important role in melanomagenesis. Cutaneous melanin content represents a major photoprotective mechanism against UVR-induced DNA damage, and generally correlates inversely with the risk of skin cancer, including melanoma. Melanoma risk is also determined by susceptibility genes, one of which is the melanocortin 1 receptor (MC1R) gene. Certain MC1R alleles are strongly associated with melanoma. We hereby present experimental evidence for the role of two melanoma risk factors, constitutive pigmentation, as assessed by total melanin, eumelanin and pheomelanin contents, and MC1R genotype and function, in determining the induction and repair of DNA photoproducts in cultured human melanocytes after irradiation with increasing doses of UVR. We found that total melanin and eumelanin contents (MC and EC) correlated inversely with the extent of UVR-induced growth arrest, apoptosis and induction of cyclobutane pyrimidine dimers (CPD), but not with hydrogen peroxide release in melanocytes expressing functional MC1R. In comparison, melanocytes with loss-of-function MC1R, regardless of their MC or EC, sustained more UVR-induced apoptosis and CPD, and exhibited reduced CPD repair. Therefore, MC, mainly EC, and MC1R function are independent determinants of UVR-induced DNA damage in melanocytes.

Conformation and polarity of the active site of xylanase I fromThermomonosporasp. as deduced by fluorescent chemoaffinity labeling

A fluorescent chemoaffinity label o-phthalaldehyde (OPTA) was used to ascertain the conformational flexibility and polarity at the active site of xylanase I (Xyl I). The kinetics of inactivation of Xyl I with OPTA revealed that complete inactivation occurred due to the binding of one molecule of OPTA to the active site of Xyl I. The formation of a single fluorescent isoindole derivative corroborated these findings. OPTA has been known to form a fluorescent isoindole derivative by crosslinking the proximal thiol and amino groups of cysteine and lysine. The involvement of cysteine in the formation of a Xyl I-isoindole derivative has been negated by fluorometric and chemical modification studies on Xyl I with group-specific reagents and by amino-acid analysis. The kinetic analysis of diethylpyrocarbonate-modified Xyl I established the presence of an essential histidine at or near the catalytic site of Xyl I. Modification of histidine and lysine residues by diethylpyrocarbonate and 2,4,6-trinitrobenzenesulfonic acid, respectively, abolished the ability of the enzyme to form an isoindole derivative with OPTA, indicating that histidine and lysine participate in the formation of the isoindole complex. A mechanism for the reaction of OPTA with histidine and lysine residues present in the protein structure has been proposed. Experimental evidence presented here suggests for the first time that the active site of Xyl I is conformationally more flexible and more easily perturbed in the presence of denaturants than the molecule as a whole. The changes in the fluorescence emission maxima of a model compound (isoindole adduct) in solvents of different polarity were compared with the fluorescence behaviour of the Xyl I-isoindole derivative, leading to the conclusion that the active site is located in a microenvironment of low polarity.

A novel thermostable xylanase from Thermomonospora sp.: influence of additives on thermostability

An alkalothermophilic Thermomonospora sp. producing high levels of xylanase was isolated from self-heating compost. The culture produced 125 IU/ml of xylanase when grown in shake flasks at pH 9 and 50 degrees C for 96 h. The culture filtrate also contained cellulase (23 IU/ml), mannanase (1 IU/ml) and beta-xylosidase (0.1 IU/ml) activities. The xylanase was active at a broad range of pH (5-9) and temperature (40-90 degrees C). The optimum pH and temperature were 7 and 70 degrees C, respectively. The enzyme was stable in the pH range 5-8 and was thermostable with half-lives of 8 and 4 h at 60 degrees C and 70 degrees C, respectively, but only 9 min at 80 degrees C. The effects of a variety of compounds to enhance the stability of xylanase at 80 degrees C was studied. Addition of sorbitol, mannitol and glycerol increased the thermostability of xylanase in proportion to the number of hydroxyl groups per polyol molecule. Glycine also offered protection against thermoinactivation. Xylan, trehalose, gelatin and trehalose-gelatin mixture had marginal effect on the thermostability of xylanase at 80 degrees C.

Studies on carboxymethyl cellulase produced by an alkalothermophilic actinomycete

A novel alkalothermophilic actinomycete having optimum growth at pH 9 and 50 degrees C was isolated from self-heating compost from the Barabanki district of Uttar Pradesh, India. Based on its morphology, susceptibility of spores to heat and novobiocin, guaninecytosine content of chromosomal DNA and cell wall composition, the organism was classified under Thermomonospora. The alkalothermophilic actinomycete produced 23 IU/ml carboxymethyl cellulase (CMCase). The CMCase was purified by fractional ammonium sulphate precipitation followed by cellulose affinity chromatography and Sephacryl S-200 gel filtration. The CMCase had a molecular weight of 38 KD and pI of 4.1. The enzyme exhibited optimum activity at pH 5 and temperature 50 degrees C. The CMCase showed pH stability in the range 7-10. The enzyme retained 100% activity at 50 degrees C for 72 h and had half-lives of 7 and 3 h at 60 degrees C and 70 degrees C, respectively. The CMCase was stable in the presence of commercial detergents such as Ariel, Henko and Surf Excel, indicating its potential as an additive to laundry detergents.

Involvement of a lysine residue in the active site of a thermostable xylanase from Thermomonospora sp

A highly thermostable xylanase (Xyl I) produced by Thermomonospora sp. was purified to homogeneity and was classified as a family 10 xylanase based on its molecular weight (38,000 Da) and isoelectric point (4.1). K2d analysis showed that the secondary structure of Xyl I was made up of 38% alpha-helix and 10% beta-sheet. The optimal temperature for the activity of Xyl I was 80 degrees C. Xyl I was highly thermostable with half-lives of 86, 30, and 15 min at 80, 90, and 100 degrees C respectively. Xyl I was stable in an expansive pH range of 5 to 10 with more than 75% residual activity. Our present investigation using o-phthalaldehyde (OPTA) as the chemical initiator for fluorescent chemoaffinity labeling and trinitrobenzenesulphonic acid (TNBS) as chemical modifier have revealed the presence of a single lysine residue in the active site of Xyl I. The high pK value for the basic limb of the pH profile reflects the ionization of a lysine residue. The higher K(m) values and similar k(cat) values of the TNBS modified enzyme in comparison to native enzyme and the substrate protection against OPTA and TNBS, suggested the presence of the lysine residue in the substrate-binding site.

Atypical meningioma: a clinicopathological analysis

In this retrospective study, 382 operated cases of meningiomas were reviewed. 32 cases (8.3%) were histopathologically classified as atypical meningioma. The anatomical locations and histological features in all the thirty-two cases were correlated with their recurrence rates and biological behaviour. The overall recurrence rate for atypical meningioma within two years was 28% as compared to 9.3% in benign meningiomas. It is being emphasized that an accurate histopathological interpretation of atypical meningioma is essential for predicting the recurrence, biological behavior as well as post-operative management modalities.

Is epilepsy surgery possible in countries with limited resources?

This study illustrates the outcome and cost-effectiveness of anterior temporal lobectomy (ATL) among patients with medically refractory temporal lobe epilepsy (TLE) treated in an epilepsy center in Kerala, South India. Patients for ATL were selected on the basis of a noninvasive protocol comprising clinical, interictal scalp electroencephalogram (EEG), magnetic resonance imaging, and ictal video-EEG data. The authors compared the outcome and direct cost of 119 patients (mean age, 25.6 years; mean duration of epilepsy before ATL, 16.1 years) who have completed at least 1 year follow-up after ATL with 71 refractory TLE patients (mean age, 27.1 years; mean duration of epilepsy, 15.4 years) who did not undergo ATL. Patients in the study who underwent ATL had a 70% likelihood of becoming seizure-free after ATL and a 30% chance of being completely off of antiepileptic drug treatment within 3 years after ATL. The out-of-pocket one-time payment for ATL (including presurgical evaluation) in this setup is Indian Rupees (INR) 47,000 (US$ 1,200). The total direct medical cost of caring for TLE patients aged 26 to 60 years would be INR 200,000 (US$ 5,000). Patients freed from seizures often can be better employed and achieve an improved quality of life. It is concluded that ATL for refractory TLE is a more cost-effective option than continued medical treatment. Epilepsy surgery is not only possible in a developing country but can also be undertaken in a cost-effective way.

Clinical and echocardiographic predictors of left atrial clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis: a prospective study in 200 patients by transesophageal echocardiography

The objective of this study was to prospectively investigate various clinical and echocardiographic variables to predict the left atrial and left atrial appendage clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis. We studied 200 consecutive patients (112 males and 88 females; mean age 29.6+/-9.6 years). Left atrial clot and spontaneous echo contrast were present in 26 and 53.5% of cases, respectively. There were no significant differences in the mitral valve area, mean transmitral diastolic gradient and left ventricular ejection fraction between patients with and without clot. Patients with clot were older (34.4+/-11.4 vs. 28.2+/-8.5 years, P<0.001), had longer duration of symptoms (41. 4+/-36.0 vs. 28.8+/-22.9 months, P<0.001), more frequent atrial fibrillation and spontaneous echo contrast (69.2 vs. 16.9%, P<0. 00001 and 76.9 vs. 45.3%, P<0.00001, respectively) and larger left atrial area and diameter (41.0+/-12.7 vs. 29.9+/-7.4 cm(2), P<0.00001 and 53.9+/-8.3 vs. 47.6+/-7.4 mm, P<0.0001, respectively) as compared to patients without clot. Similarly patients with spontaneous echo contrast were older (31+/-10.4 vs. 27.8+/-8.3 years, P<0.01), had more frequent atrial fibrillation (48.6 vs. 9.7%, P<0.0001), left atrial clot (37.4 vs. 12.9%, P<0.0001), larger left atrial area and diameter (37.6+/-11.2 vs. 28.1+/-6.7 cm(2), P<0.00001 and 52.2+/-8.3 vs. 45.9+/-6.5 mm, P<0.00001, respectively) and smaller mitral valve area (0.77+/-0.14 vs. 0.84+/-0.13 cm(2), P<0.01) as compared to patients without spontaneous echo contrast. There were no significant differences in the mean transmitral diastolic gradient and left ventricular ejection fraction. On multiple regression and discriminant function analysis, atrial fibrillation and left atrial area were independent predictors of left atrial clot formation. In a subgroup of patients with sinus rhythm, larger left atrial area and presence of spontaneous echo contrast were significantly associated with the presence of clot in left atrium and appendage. We conclude that in patients with severe mitral stenosis, the presence of atrial fibrillation and in the subgroup of the patients with sinus rhythm the presence of large left atrium (> or =40 cm(2)) and spontaneous echo contrast were associated with higher risk of clot formation in the left atrium and might be benefited by prophylactic anticoagulation.

Juvenile tricuspid stenosis and rheumatic tricuspid valve disease: an echocardiographic study

Tricuspid valve involvement is not uncommon in patients with rheumatic heart disease and is frequently missed on routine clinical examination. We prospectively studied the echocardiographic profile of tricuspid valve disease in 788 consecutive patients with rheumatic heart disease. Out of these patients 9% (70) had tricuspid valve disease and 55.7% (39) of these were of < or = 20 years of age. Of these 60% were females and 40% were males. Their ages ranged from 9 to 64 years (mean 24.2+/-13.6 years). Of these patients, 50% had tricuspid stenosis with or without tricuspid regurgitation whereas 50% had isolated tricuspid regurgitation. Isolated tricuspid stenosis was present in 7.4% of these cases. All patients had associated mitral stenosis. Severe mitral stenosis was present more commonly in patients with juvenile tricuspid stenosis compared to older patients (94.1% vs. 55.6%, P<0.005). Mitral regurgitation was present more commonly in juvenile age group patients compared to older patients (53.8% vs. 25.8%, P<0.01). A combination of mitral, aortic and tricuspid stenosis was present in five cases and four of these were in the juvenile age group. Left ventricular enlargement and dysfunction were present in 28.6 and 14.3% patients, respectively, and the majority of these patients were in the juvenile age group (P<0.05). We conclude that rheumatic tricuspid valve disease occurs early in the course of the disease and progresses faster in India and is always associated with mitral stenosis. Juvenile tricuspid stenosis is more commonly associated with severe mitral stenosis, mitral regurgitation, left ventricular enlargement and dysfunction as compared with older patients.

Pathology of temporal lobe epilepsy: An analysis of 100 consecutive surgical specimens from patients with medically refractory epilepsy

The neuropathological features of temporal lobe epilepsy were studied utilising 100 consecutive surgical specimens from patients with medically refractory complex partial seizures. A wide spectrum of neuropathological changes was recorded in 98 specimens. Fifty-eight specimens showed features of Ammon's horn sclerosis. Diffuse accumulation of corpora amylacea were demonstrated in the resected temporal lobes from 54 patients. Six patients had neoplastic lesions of temporal lobe. One unique case of dysembryoplastic neuroepithelial tumour showed a melanotic component within the tumour. The neuropathological features were regarded as nonspecific in 31% of cases. Our results indicate that a majority of patients with medically intractable epilepsy of temporal lobe origin reveal significant neuropathological features. Careful documentation of the neuropathological features and its correlation with radiological, electrophysiological and pre- and post-surgical clinical features will help in predicting the seizure outcome after temporal lobectomy for medically refractory epilepsy.

Molecular and biotechnological aspects of microbial proteases

Proteases represent the class of enzymes which occupy a pivotal position with respect to their physiological roles as well as their commercial applications. They perform both degradative and synthetic functions. Since they are physiologically necessary for living organisms, proteases occur ubiquitously in a wide diversity of sources such as plants, animals, and microorganisms. Microbes are an attractive source of proteases owing to the limited space required for their cultivation and their ready susceptibility to genetic manipulation. Proteases are divided into exo- and endopeptidases based on their action at or away from the termini, respectively. They are also classified as serine proteases, aspartic proteases, cysteine proteases, and metalloproteases depending on the nature of the functional group at the active site. Proteases play a critical role in many physiological and pathophysiological processes. Based on their classification, four different types of catalytic mechanisms are operative. Proteases find extensive applications in the food and dairy industries. Alkaline proteases hold a great potential for application in the detergent and leather industries due to the increasing trend to develop environmentally friendly technologies. There is a renaissance of interest in using proteolytic enzymes as targets for developing therapeutic agents. Protease genes from several bacteria, fungi, and viruses have been cloned and sequenced with the prime aims of (i) overproduction of the enzyme by gene amplification, (ii) delineation of the role of the enzyme in pathogenecity, and (iii) alteration in enzyme properties to suit its commercial application. Protein engineering techniques have been exploited to obtain proteases which show unique specificity and/or enhanced stability at high temperature or pH or in the presence of detergents and to understand the structure-function relationships of the enzyme. Protein sequences of acidic, alkaline, and neutral proteases from diverse origins have been analyzed with the aim of studying their evolutionary relationships. Despite the extensive research on several aspects of proteases, there is a paucity of knowledge about the roles that govern the diverse specificity of these enzymes. Deciphering these secrets would enable us to exploit proteases for their applications in biotechnology.

Long-term outcome of intracoronary microstent implantation: lesion matched comparison with Palmaz-Schatz stent

We performed a lesion matched comparison of AVE Microstent and Palmaz-Schatz stent implants with 6 month follow-up angiography to compare the occurrence of restenosis. Thirty-three pairs of lesions were matched for lesion location, ACC/AHA lesion type, reference diameter, lesion length, and angiographic descriptors. Age, sex, clinical profile, and indication for stenting were comparable. Quantitative coronary analysis before and after the procedure was comparable in the two groups but minimum lumen diameter (MLD) at follow-up was less with Microstent--2.01 +/- 1.01 mm than Palmaz-Schatz stent--2.43 +/- 0.96 mm (P = 0.05). Binary restenosis was present in 33% and 21% and was diffuse in 55% and 29% of the two groups, respectively. Typical angina at follow-up was more frequent with Microstent (36%) than Palmaz-Schatz stent (15%; P = 0.038). When implanted in lesions of similar complexity, Microstent yields similar post procedure angiographic results but smaller MLD at follow-up and more frequent angina than Palmaz-Schatz stent.

A result on a 2 x 2 survival experiment

Lifetime data classified according to categorical variables under the proportionality of the hazard functions of response variables for various treatment combinations is assumed. The proposed model is a combination of Cox's proportional hazards model and ANOVA model. The existence of a solution to the marginal likelihood function is examined for the case of 2 x 2 two-way classification. We provide an easily verifiable condition for the existence of a unique estimate.

Conformation and microenvironment of the active site of xylose reductase inferred by fluorescent chemoaffinity labeling

Conformation and microenvironment at the active site of xylose reductase (XR) from Neurospora crassa was probed with fluorescent chemoaffinity labeling (FCAL) using o-phthalaldehyde as a chemical initiator. Formation of a single isoindole derivative resulted in complete inactivation of the enzyme as judged by spectroscopic and fluorescence studies. Kinetic analysis of the 2,4,6-trinitrobenzenesulfonic-acid-modified XR implicated the presence of an essential lysine residue at the active site of XR. Modification of lysine in XR abolished the ability of the enzyme to form isoindole derivative, indicating that the lysine residue involved in the reaction with 2,4,6-trinitrobenzenesulfonic acid and o-phthalaldehyde is the same and that the probe o-phthalaldehyde is directed to the active site. Fluorescence studies revealed that inactivation of XR by Gdn/HCl precedes gross conformational change and the possibility of secondary-conformational change was eliminated by acrylamide quenching studies. The enzyme inactivated by low concentrations of Gdn/HCl retained its ability to form the fluorescent XR-isoindole derivative indicating that inactivation is not due to conformational changes at or near the active site of XR. Gdn/HCl also had no effect on the high-affinity and low-affinity NADPH-binding sites of XR. Energy-transfer experiments further revealed structural integrity at the active site of the Gdn/HCl-inactivated XR. Changes in the fluorescence emission maximum of 1-(beta-hydroxyethylthio)-2-beta hydroxyethyl isoindole (EA adduct) in solvents of varying polarity was studied, the data obtained were utilized to interpret the fluorescence behaviour of XR-isoindole derivative and assess the polarity at the active site. Experimental evidence presented here serves to suggest that the inactivation of XR by Gdn/HCl precedes conformational changes at the active site located in a microenvironment of low polarity.

Suprasellar meningioma subsequent to treatment for a pituitary adenoma: case report

The authors report a case of suprasellar meningioma that developed 16 years after surgery and radiation therapy for a pituitary adenoma. The patient had significant recovery of visual loss following excision of the meningioma. We believe that this tumor was induced by radiation received by the patient previously and we stress that tissue diagnosis should be obtained in patients who develop a recurrent tumor after a long period following initial radiotherapy. Radiation induced meningioma has to be considered in the differential diagnosis of any patient who has a recurrence after therapeutic radiation. This is especially essential in the absence of biochemical and clinical signs of a previously functioning pituitary adenoma and before the initiation of medical therapy for recurrent pituitary adenomas.

Molecular and industrial aspects of glucose isomerase

Glucose isomerase (GI) (D-xylose ketol-isomerase; EC. 5.3.1.5) catalyzes the reversible isomerization of D-glucose and D-xylose to D-fructose and D-xylulose, respectively. The enzyme has the largest market in the food industry because of its application in the production of high-fructose corn syrup (HFCS). HFCS, an equilibrium mixture of glucose and fructose, is 1.3 times sweeter than sucrose and serves as a sweetener for use by diabetics. Interconversion of xylose to xylulose by GI serves a nutritional requirement in saprophytic bacteria and has a potential application in the bioconversion of hemicellulose to ethanol. The enzyme is widely distributed in prokaryotes. Intensive research efforts are directed toward improving its suitability for industrial application. Development of microbial strains capable of utilizing xylan-containing raw materials for growth or screening for constitutive mutants of GI is expected to lead to discontinuation of the use of xylose as an inducer for the production of the enzyme. Elimination of Co2+ from the fermentation medium is desirable for avoiding health problems arising from human consumption of HFCS. Immobilization of GI provides an efficient means for its easy recovery and reuse and lowers the cost of its use. X-ray crystallographic and genetic engineering studies support a hydride shift mechanism for the action of GI. Cloning of GI in homologous as well as heterologous hosts has been carried out, with the prime aim of overproducing the enzyme and deciphering the genetic organization of individual genes (xylA, xylB, and xylR) in the xyl operon of different microorganisms. The organization of xylA and xylB seems to be highly conserved in all bacteria. The two genes are transcribed from the same strand in Escherichia coli and Bacillus and Lactobacillus species, whereas they are transcribed divergently on different strands in Streptomyces species. A comparison of the xylA sequences from several bacterial sources revealed the presence of two signature sequences, VXW(GP)GREG(YSTAE)E and (LIVM)EPKPX(EQ)P. The use of an inexpensive inducer in the fermentation medium devoid of Co2+ and redesigning of a tailor-made GI with increased thermostability, higher affinity for glucose, and lower pH optimum will contribute significantly to the development of an economically feasible commercial process for enzymatic isomerization of glucose to fructose. Manipulation of the GI gene by site-directed mutagenesis holds promise that a GI suitable for biotechnological applications will be produced in the foreseeable future.

Molecular and industrial aspects of glucose isomerase

Glucose isomerase (GI) (D-xylose ketol-isomerase; EC. 5.3.1.5) catalyzes the reversible isomerization of D-glucose and D-xylose to D-fructose and D-xylulose, respectively. The enzyme has the largest market in the food industry because of its application in the production of high-fructose corn syrup (HFCS). HFCS, an equilibrium mixture of glucose and fructose, is 1.3 times sweeter than sucrose and serves as a sweetener for use by diabetics. Interconversion of xylose to xylulose by GI serves a nutritional requirement in saprophytic bacteria and has a potential application in the bioconversion of hemicellulose to ethanol. The enzyme is widely distributed in prokaryotes. Intensive research efforts are directed toward improving its suitability for industrial application. Development of microbial strains capable of utilizing xylan-containing raw materials for growth or screening for constitutive mutants of GI is expected to lead to discontinuation of the use of xylose as an inducer for the production of the enzyme. Elimination of Co2+ from the fermentation medium is desirable for avoiding health problems arising from human consumption of HFCS. Immobilization of GI provides an efficient means for its easy recovery and reuse and lowers the cost of its use. X-ray crystallographic and genetic engineering studies support a hydride shift mechanism for the action of GI. Cloning of GI in homologous as well as heterologous hosts has been carried out, with the prime aim of overproducing the enzyme and deciphering the genetic organization of individual genes (xylA, xylB, and xylR) in the xyl operon of different microorganisms. The organization of xylA and xylB seems to be highly conserved in all bacteria. The two genes are transcribed from the same strand in Escherichia coli and Bacillus and Lactobacillus species, whereas they are transcribed divergently on different strands in Streptomyces species. A comparison of the xylA sequences from several bacterial sources revealed the presence of two signature sequences, VXW(GP)GREG(YSTAE)E and (LIVM)EPKPX(EQ)P. The use of an inexpensive inducer in the fermentation medium devoid of Co2+ and redesigning of a tailor-made GI with increased thermostability, higher affinity for glucose, and lower pH optimum will contribute significantly to the development of an economically feasible commercial process for enzymatic isomerization of glucose to fructose. Manipulation of the GI gene by site-directed mutagenesis holds promise that a GI suitable for biotechnological applications will be produced in the foreseeable future.

Purification, kinetic characterization and involvement of tryptophan residue at the NADPH binding site of xylose reductase from Neurospora crassa

Xylose reductase (XR) from Neurospora crassa was purified to homogeneity and was found to be specific to NADPH (nicotinamide adenine dinucleotide phosphate). The purified enzyme showed M(r) of 60 and 29 kDa by gel filtration and SDS-PAGE indicating the presence of two subunits. The kinetic mechanism of xylose reductase is 'iso-ordered bi bi'. Inactivation of XR by N-bromosuccinimide (NBS) was found to be biphasic with second-order rate constants of 2.5 x 10(2) and 80 M-1S-1 for the fast (kf) and slow phase (ks), respectively. NADPH protected 90% of XR activity against inhibition by NBS. The fluorescence and circular dichroism (CD) studies revealed that inactivation was not due to gross conformational change in the enzyme. Analysis of the modified Stern-Volmer plot indicated that 49% of the tryptophanyl fluorescence was available for quenching which was completely abolished in the presence of NADPH confirming the involvement of tryptophan at the coenzyme binding site. Experimental evidence presented here serves to implicate the involvement of a tryptophan residue at the low-affinity NADPH binding site and the nature of this site has been assessed by using the hydrophobic probe ANS.

Craniospinal and spinal enterogenous cysts--report of three cases

We report three cases of enterogenous cyst, one craniospinal and two spinal manifesting with features of spinal cord compression. In one the cyst was intramedullary in location and in the other two it was intradural, extramedullary. The unusual clinical presentation, location and magnetic resonance imaging (MRI) characteristics are discussed. None of the three patients had any vertebral anomaly or other congenital malformation. All patients had excellent outcome following surgery.

Prevalence of diabetes in the young in south India

Students from nine schools and one college in Madras city, were screened for diabetes by oral glucose tolerance test. The criteria recommended by the World Health Organization was adopted to classify glucose tolerance. Among 3,515 students, between 5 and 19 years of age, participated in this survey, 1982 (56.4%) were males and 1.533 were (43.6%) females. Family history of diabetes was positive in 302 (8.6%) students. There was no overt case of diabetes of any type. Three (0.09%) males had renal glycosuria. It is therefore concluded that insulin-dependent diabetes, non-insulin dependent diabetes or any other type of diabetes in the young is rare in South India.

Significance of the N-6/N-3 ratio for insulin action in diabetes

This report supplies supportive data for the hypothesis that a high n-6/n-3 dietary fat ratio is a potent, negative variable in NIDDM. Further work is necessary to critically evaluate this hypothesis.

Characterization and sequencing of an active-site cysteine-containing peptide from the xylanase of a thermotolerant Streptomyces

The kinetics of chemical modification of the xylanase from a thermotolerant Streptomyces T7 indicated the involvement of 1 mol of cysteine residue/mol of enzyme [Keskar, Srinivasan & Deshpande (1989) Biochem. J. 261, 49-55]. The chromophoric reagent N-(2,4-dinitroanilino)maleimide (DAM) reacts covalently with thiol groups of xylanase with complete inactivation. Protection against inactivation was provided by the substrate (xylan). The purified xylanase that had been modified with DAM was digested with pepsin and the peptides were purified by gel filtration followed by peptide mapping. The active-site peptide was distinguished from the other thiol-containing peptides by comparison of the peptides generated by labelling the enzyme in the presence and in the absence of the substrate. The peptide mapping of the modified enzyme in the absence of xylan showed three yellow peptides, whereas in the presence of xylan only two yellow peptides were detected. The active-site peptide protected by the substrate failed to form the complex with DAM. The modified active-site peptide was isolated and sequenced. Gas-phase sequencing provided the following sequence: Ser-Val-Ile-Met-Xaa-Ile-Asp-His-Ile-Arg-Phe. This is the first report on the isolation and sequencing of the active-site peptide from a xylanase. The comparison of reactive cysteine-containing peptide sequence with the catalytic regions of other glucanases revealed the presence of a conserved aspartic acid residue.

Hyperglycemia-induced activation of human erythrocyte aldose reductase and alterations in kinetic properties

Incubation of human erythrocytes with varying concentrations of glucose resulted in a several-fold increase in aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21) activity as determined by the rate of NADPH oxidation and the rate of sorbitol formation. As compared to aldose reductase from human erythrocytes not incubated with glucose (native enzyme), aldose reductase from 30 mM glucose-incubated erythrocytes (activated enzyme) exhibited altered kinetic and inhibition properties. Native enzyme showed biphasic kinetics with substrates (glucose and glyceraldehyde), was strongly inhibited by 15 microM ADP, 1,3-diphosphoglycerate, 2,3-diphosphoglycerate and 3-phosphoglycerate, and aldose reductase inhibitors such as sorbinil and alrestatin. The activated enzyme, on the other hand, exhibited monophasic kinetics, low Km for substrates, was not inhibited by the phosphorylated intermediates, and was less susceptible to inhibition by aldose reductase inhibitors. In erythrocytes of the diabetic subjects, we have found an excellent correlation between aldose reductase activity and plasma glucose levels and have observed that whenever the blood glucose level was higher than 15 mM, all of the erythrocyte aldose reductase was present in the activated form and exhibited properties similar to those observed with aldose reductase obtained from 30 mM glucose-incubated erythrocytes.

Primary hypothyroidism in chronic renal failure

Serum thyroid hormone concentrations have been measured in 8 patients with chronic renal failure (CRF) who are currently enrolled on a chronic hemodialysis program. Three of these patients were diagnosed to be suffering from coexistent primary hypothyroidism whereas the other 5 were considered euthyroid. There was a variable decline in serum thyroid hormone levels in both groups. However, the serum TSH response to TRH was normal or blunted in the euthyroid group but was characteristically brisk in subjects with CRF and coexistent primary hypothyroidism. The TRH test may be useful in the diagnosis of primary hypothyroidism coexistent with CRF.

Incidence of tempero-mandibular joint pain dysfunction syndrome in rural population

The incidence and clinical course of the tempero-mandibular joint dysfunction syndrome was studied among 1187 subjects over the age of 16, who attended the rural dental consultations held at various places in the State of Karnataka, India. The study revealed an incidence of 20.3%. Contracy to earlier reports, the incidence was higher in males than in females and more married females were affected than unmarried. Clicking appeared to be the predominant symptom in all age groups. The incidence of pain increased with age. Of all patients 43.75% were not aware of a clicking joint; 53.7% persons with clicking and 14% with pain were not disturbed by their symptoms. The findings of the study failed to establish any relationship between unilateral missing teeth and the occurrence of the pain dysfunction syndrome (PDS). The chewing habits (betel leaf, tobacco, betel nut) which are prevalent in India appeared to have no effect on the incidence of PDS. It is suggested that more epidemiological studies should be carried out in different parts of the world with varying social, political and economic systems to enable better understanding of the global incidence of PDS.

Vasopressin and oxytocin content of human fetal brain at different stages of gestation

Pituitaries from 38 human fetuses and 5 microdissected hypothalamic areas from each of 14 fetuses were assayed for vasopressin and oxytocin. The fetuses were between 15 and 34 weeks of gestation. Vasopressin and oxytocin were found in all the pituitary glands and all the hypothalamic areas studied. A trend of increasing content of both hormones was found in the pituitary gland towards the end of gestation with a marked increase in vasopressin/oxytocin ratio. The human fetus synthesizes oxytocin and vasopressin at least from 15 weeks of gestation and the presence of both hormones in the hypothalamus is not limited to the supraoptic and paraventricular nuclei.