Obstetric anaesthesiology: manpower and service provision issues in India

Obstetric anaesthesiologists play a pivotal role as peripartum physicians steering the team of obstetric healthcare providers towards a continuum of medical education, enhanced training and safer patient care. However, in resource-limited countries, deficiency of human resources and hence services available poses challenges to those attempting to reduce maternal mortality rates. Measures to fill the gap include creating a cadre of uniformly well-trained and certified non-physician anaesthesia providers (NPAPs) supervised by a physician obstetric anaesthesiologist and well-equipped rural and urban health care facilities. The Association of Obstetric Anaesthesiologists of India needs to upscale their outreach programs with regular knowledge updates and practical skill training to the NPAPs, medical graduates and postgraduate doctors in these regions. A combination of strong local administrative will, legislation for the provision of essential supplies and a global collaborative effort using checklists and protocols may help to stem gaps in the provision of safe maternal care.

Use of the Arctic Sun™ 5000 targeted temperature management system to achieve rewarming during a prolonged hypothermic cardiorespiratory arrest

Cardiorespiratory arrest due to severe hypothermia may require prolonged cardiopulmonary resuscitation whilst the patient is rewarmed. There are reported cases of successful resuscitation with good neurological outcomes after prolonged arrests and resuscitation up to 9 h. However, in the majority of these cases, extracorporeal life support was used to maintain perfusion and rewarm the patient. Here, we report a case of successful cardiopulmonary resuscitation lasting 6.5 h, following cardiac arrest secondary to severe hypothermia, with rewarming using an Arctic Sun™ 5000. The Arctic Sun 5000 is a targeted temperature management device which is conventionally used to prevent hyperthermia post-cardiac arrest. In this report, we discuss the reasons why the device was used in this case and the effects of severe hypothermia on cardiac arrest management. We believe that this is the longest reported successful cardiopulmonary resuscitation in a severely hypothermic patient without the use of extracorporeal life support.

Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

The Relationship Between Dreams and Subsequent Morning Mood Using Self-Reports and Text Analysis

While material from waking life is often represented in dreams, it is less clear whether and how dreams impact waking life. Here, we assessed whether dream mood and content from home diaries predict subsequent waking mood using both subjective self-reports and an objective automated word detection approach. Subjective ratings of dream and morning mood were highly correlated within participants for both negative and positive valence, suggesting that dream mood persists into waking. Text analyses revealed similar relationships between affect words in dreams and morning mood. Moreover, dreams referencing death or the body were related to worse morning mood, as was first-person singular pronoun usage (e.g., "I"). Dreams referencing leisure or ingestion, or including first-person plural pronouns (e.g., "we"), were related to better morning mood. Together, these results suggest that subjective experiences during sleep, while often overlooked, may be an important contributor to waking mood.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42761-021-00080-8.

Gold Chain Formation via Local Lifting of Surface Reconstruction by Hot Electron Injection on H2(D2)/Au(111)

The hexagonal close packed surface of gold shows a 22 × 3 "herringbone" surface reconstruction which makes it unique among the (111) surfaces of all metals. This long-range energetically favored dislocation pattern appears in response to the strong tensile stress that would be present on the unreconstructed surface. Adsorption of molecular and atomic species can be used to tune this surface stress and lift the herringbone reconstruction. Here we show that herringbone reconstruction can be controllably lifted in ultrahigh vacuum at cryogenic temperatures by precise hot electron injection in the presence of hydrogen molecules. We use the sharp tip of a scanning tunneling microscope (STM) for charge carrier injection and characterization of the resulting chain nanostructures. By comparing STM images, rotational spectromicroscopy and ab initio calculations, we show that formation of gold atomic chains is associated with release of gold atoms from the surface, lifting of the reconstruction, dissociation of H₂ molecules, and formation of surface hydrides. Gold hydrides grow in a zipper-like mechanism forming chains along the [11̅0] directions of the Au(111) surface and can be manipulated by further electron injection. Finally, we demonstrate that Au(111) terraces can be transformed with nearly perfect terrace selectivity over distances of hundreds of nanometers.

Risk of brainstem necrosis in pediatric patients with central nervous system malignancies after pencil beam scanning proton therapy

Background: Radiation therapy (RT) plays an important role in management of pediatric central nervous system (CNS) malignancies. Centers are increasingly utilizing pencil beam scanning proton therapy (PBS-PT). However, the risk of brainstem necrosis has not yet been reported. In this study, we evaluate the rate of brainstem necrosis in pediatric patients with CNS malignancies treated with PBS-PT.Material and methods: Pediatric patients with non-hematologic CNS malignancies treated with PBS-PT who received dose to the brainstem were included. All procedures were approved by the institutional review board. Brainstem necrosis was defined as symptomatic toxicity. The actuarial rate was analyzed by the Kaplan Meier method.Results: One hundred and sixty-six consecutive patients were reviewed. Median age was 10 years (range 0.5-21 years). Four patients (2.4%) had prior radiation. Median maximum brainstem dose in the treated course was 55.4 Gy[RBE] (range 0.15-61.4 Gy[RBE]). In patients with prior RT, cumulative median maximum brainstem dose was 98.0 Gy [RBE] (range 17.0-111.0 Gy [RBE]). Median follow up was 19.6 months (range, 2.0-63.0). One patient who had previously been treated with twice-daily radiation therapy and intrathecal (IT) methotrexate experienced brainstem necrosis. The actuarial incidence of brainstem necrosis was 0.7% at 24 months (95% CI 0.1-5.1%).Conclusion: The rate of symptomatic brainstem necrosis was extremely low after treatment with PBS-PT in this study. Further work to clarify clinical and dosimetric parameters associated with risk of brainstem necrosis after PBS-PT is needed.

A Single Hydrogen Molecule as an Intensity Chopper in an Electrically Driven Plasmonic Nanocavity

Photon statistics is a powerful tool for characterizing the emission dynamics of nanoscopic systems and their photophysics. Recent advances that combine correlation spectroscopy with scanning tunneling microscopy induced luminescence (STML) have allowed the measurement of the emission dynamics from individual molecules and defects, demonstrating their nature as single-photon emitters. The application of correlation spectroscopy to the analysis of the dynamics of a well-characterized adsorbate system in an ultrahigh vacuum remained to be demonstrated. Here, we combine single-photon time correlations with STML to measure the dynamics of individual H₂ molecules between a gold tip and an Au(111) surface. An adsorbed H₂ molecule performs recurrent excursions below the tip apex. We use the fact that the presence of the H₂ molecule in the junction modifies plasmon emission to study the adsorbate dynamics. Using the H₂ molecule as a chopper for STM-induced optical emission intensity, we demonstrate bunching in the plasmonic photon train in a single measurement over 6 orders of magnitude in the time domain (from microseconds to seconds) that takes only a few seconds. Our findings illustrate the power of using photon statistics to measure the diffusion dynamics of adsorbates with STML.

Differential promoter methylation of DAZL gene in bulls with varying seminal parameters

In India, cross-breeding of indigenous cattle with exotic cattle such as Holstein Friesian and Jersey has been going on since last four decades to improve milk production. Although it has led to increased milk yield, the subfertility in male cross-bred progeny has remained a significant problem. Epigenetic modifications (DNA methylation, histone modifications and chromatin remodelling) are regarded as key players influencing gene expression. DAZL gene plays an important role in germline development and gametogenesis. The methylation and mRNA expression level of this gene have been significantly negatively correlated in the testes of cattle-yak hybrids and their parents. This study analysed the methylation profile of DAZL gene promoter in bull spermatozoa in an attempt to speculate its role in cross-bred cattle subfertility. Semen samples from Sahiwal, Holstein Friesian and Frieswal bulls (Sahiwal X Holstein Friesian) with varying semen motility parameters were collected, and DNA was isolated. Methylation-specific primers were used to amplify part of promoter and exon 1 of DAZL gene using bisulphite-converted DNA. The amplified products were sequenced after cloning in pTZ57R/T vector. Sequence analysis revealed significantly higher DNA methylation of DAZL gene in Frieswal bulls with poor motility (28.26%) as compared to medium (15.21%) and high motility phenotype (6.52%). In pure-bred counterparts, Sahiwal and Holstein Friesian, epigenetic marks were more in the former (15.21%) than the latter (4.34%), but in both cases, the values were lower as compared to the poor motility Frieswal bulls. This suggests that differential hypermethylation of the CpG islands could possibly influence reproductive parameters in bovines.

Remote monitoring of blood pressure to reduce the risk of preeclampsia related complications with an innovative use of mobile technology

OBJECTIVE

Assess suitability of remote self-monitoring of blood pressure with an innovative use of technology in detecting raised blood pressure in pregnancy.

STUDY DESIGN

Assess ease of use and safety of the newly developed kit which included a Bluetooth enabled blood pressure machine and an android based mobile phone. The phone was modified to have only one application in it which showed the blood pressure readings with a traffic light system. The study was a proof of concept for wider use of the kit. We provided 50 women who were admitted with the kit. We assessed ease of use of the blood pressure machine and accuracy of readings including remote transfer to a computer.

MAIN OUTCOME MEASURE

Technological feasibility and acceptance by women.

RESULTS

The technology provides accurate data and visual cues including safe remote transfer instantaneously. 90% of the women agreed that the Kit was simple to use and 78% would prefer this model of testing at home.

CONCLUSION

In a relatively resource rich setting the machine can reduce the number of patient visits for women who are at risk for preeclampsia. In resource poor settings it helps to triage resources to women who need it the most. It also is a valuable tool for research. Studies of the Kit in both developed and developing world will be needed to show reduction in perinatal and maternal morbidity or mortality secondary to preeclampsia.

Status of Lipid Peroxidation, Some Antioxidant Enzymes and Erythrocytic Fragility of Crossbred Cattle Naturally Infected with Theileria annulata

Erythrocytic lipid peroxidation, activities of some antioxidant enzymes and osmotic fragility of red blood cells was studied in adult (>1 year) crossbred cattle naturally infected with Theileria annulata. Twenty clinically healthy animals (group I) and 15 clinical cases (group II) of tropical theileriosis were selected. Cattle suffering from theileriosis had significantly higher (p<0.01) erythrocytic lipid peroxidation and osmotic fragility. Activities of antioxidant enzymes, viz. glucose-6-phosphate dehydrogenase (G6PD) and glutamate peroxidase (GPx) were also significantly increased (p<0.01) in group II. However, superoxide dismutase and catalase did not show significant changes. The results indicated that infection with theileria led to increased oxidative stress to the animals, and even a significant rise in the activities of antioxidant enzymes. G6PD and GPx could not lower this oxidative stress. However, the increase in the activities of antioxidant enzymes pointed towards the body's defence mechanism against lipid peroxidation during oxidative stress in theileriosis.

Three-legged pair of pants anastomosis: a rare technique for renal transplantation

Because of the shortage of donors, kidneys previously judged to be unsuitable are now accepted for transplantation. Successful engraftment of kidneys with multiple renal arteries is one of the challenges and requires meticulous vascular surgical technique. In one of our case of renal allograft with three renal arteries, we created a single lumen by suturing three arteries together, like a three-legged pair of pants. The end of the single lumen was anastomesed to the side of external iliac artery. There was brisk diuresis on table after transplantation. Postoperatively, the patient had an uneventful course and normal graft function.

Identification of ARAP3, a novel PI3K effector regulating both Arf and Rho GTPases, by selective capture on phosphoinositide affinity matrices

We show that matrices carrying the tethered homologs of natural phosphoinositides can be used to capture and display multiple phosphoinositide binding proteins in cell and tissue extracts. We present the mass spectrometric identification of over 20 proteins isolated by this method, mostly from leukocyte extracts: they include known and novel proteins with established phosphoinositide binding domains and also known proteins with surprising and unusual phosphoinositide binding properties. One of the novel PtdIns(3,4,5)P3 binding proteins, ARAP3, has an unusual domain structure, including five predicted PH domains. We show that it is a specific PtdIns(3,4,5)P3/PtdIns(3,4)P2-stimulated Arf6 GAP both in vitro and in vivo, and both its Arf GAP and Rho GAP domains cooperate in mediating PI3K-dependent rearrangements in the cell cytoskeleton and cell shape.

Effects of alpha-methyl-para-tyrosine-induced catecholamine depletion in patients with seasonal affective disorder in summer remission

Noradrenergic and dopaminergic mechanisms have been proposed for the pathophysiology of seasonal affective disorder (SAD). We investigated the effects of catecholamine depletion using alpha-methyl-para-tyrosine (AMPT), an inhibitor of tyrosine hydroxylase, in patients with SAD in natural summer remission. Nine drug-free patients with SAD by DSM-IV criteria, in summer remission for at least eight weeks, completed a double-blind, crossover study. Behavioral ratings and serum HVA and MHPG levels were obtained for 3-day sessions during which patients took AMPT or an active control drug, diphenhydramine. The active AMPT session significantly reduced serum levels of HVA and MHPG compared with the control diphenhydramine session. The AMPT session resulted in higher depression ratings with all nine patients having significant clinical relapse, compared with two patients during the diphenhydramine session. All patients returned to baseline scores after drug discontinuation. Catecholamine depletion results in significant clinical relapse in patients with SAD in the untreated, summer-remitted state. AMPT-induced depressive relapse may be a trait marker for SAD, and/or brain catecholamines may play a direct role in the pathogenesis of SAD.

An open trial of light therapy for women with seasonal affective disorder and comorbid bulimia nervosa

OBJECTIVE

Many patients with seasonal affective disorder (SAD) have dysfunctional eating behaviors. Conversely, many women with bulimia nervosa have marked winter worsening of mood and bulimic symptoms. Controlled studies of light therapy in SAD and in bulimia nervosa have shown beneficial effects on mood and binge/purge symptoms. We explored the clinical use of light therapy in women with SAD who also had comorbid bulimia nervosa.

METHOD

Twenty-two female patients diagnosed using DSM-IV criteria with both bulimia nervosa and major depressive disorder with a seasonal (winter) pattern were treated with an open design, 4-week trial of light therapy (10,000 lux fluorescent light box with an ultraviolet filter, 30 to 60 minutes per day in the early morning). Patients were assessed before and after treatment with depression scales and with binge/purge diaries.

RESULTS

Light therapy resulted in significant improvement in mood, with a mean 56% reduction in 29-item Hamilton Rating Scale for Depression scores following treatment (p < .001). The frequency of binges and purges per week also significantly decreased (p < .001) from baseline by a mean of 46% and 36%, respectively. Two (9%) of 22 patients became abstinent of binge/ purge episodes, compared with 10 (45%) of 22 patients who met criteria for remission of depressive symptoms. The light therapy was well tolerated by patients.

CONCLUSION

These results suggest that therapeutic effects of light therapy on mood and bulimic symptoms in patients with SAD and comorbid bulimia nervosa are sustained over at least 4 weeks. However, the low abstinence rate in bulimic symptoms indicates that light therapy may be most effectively used as an adjunctive treatment to medications and/or psychotherapy for bulimia nervosa.

DAPP1 undergoes a PI 3-kinase-dependent cycle of plasma-membrane recruitment and endocytosis upon cell stimulation

BACKGROUND

Phosphoinositide (PI) 3-kinase and its second messenger products, phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) and phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P(2)), play important roles in signalling processes crucial for cell movement, differentiation and survival. Previously, we isolated a 32kDa PtdIns(3,4,5)P(3)-binding protein from porcine leukocytes. This protein contains an amino-terminal Src homology 2 (SH2) domain and a carboxy-terminal pleckstrin homology (PH) domain, and is identical to the recently described DAPP1 (also known as PHISH or Bam32) protein. Here, we characterised the subcellular distribution of DAPP1 in response to cell stimulation.

RESULTS

When expressed transiently in porcine aortic endothelial (PAE) cells, DAPP1 translocated from the cytosol to the plasma membrane in response to platelet-derived growth factor (PDGF). This translocation was dependent on both PI 3-kinase activity and an intact DAPP1 PH domain. Following recruitment to the plasma membrane, DAPP1 entered the cell in vesicles. Similar responses were seen in DT40 chicken B cells following antibody treatment, and Rat-1 fibroblasts following epidermal growth factor (EGF) or PDGF treatment. Colocalisation studies in PAE cells suggested entry of DAPP1 by endocytosis in a population of early endosomes containing internalised PDGF-beta receptors. DAPP1 also underwent PI 3-kinase-dependent phosphorylation on Tyr139 in response to PDGF stimulation, and this event was involved in the vesicular response.

CONCLUSIONS

This is the first report of plasma-membrane recruitment and endocytosis of a PI 3-kinase effector protein in response to cell stimulation. The results suggest a novel role for DAPP1 in endosomal trafficking or sorting.

Cloning, heterologous expression, and distinct substrate specificity of protein farnesyltransferase from Trypanosoma brucei

Protein prenylation occurs in the protozoan that causes African sleeping sickness (Trypanosoma brucei), and the protein farnesyltransferase appears to be a good target for developing drugs. We have cloned the alpha- and beta-subunits of T. brucei protein farnesyltransferase (TB-PFT) using nucleic acid probes designed from partial amino acid sequences obtained from the enzyme purified from insect stage parasites. TB-PFT is expressed in both bloodstream and insect stage parasites. Enzymatically active TB-PFT was produced by heterologous expression in Escherichia coli. Compared with mammalian protein farnesyltransferases, TB-PFT contains a number of inserts of >25 residues in both subunits that reside on the surface of the enzyme in turns linking adjacent alpha-helices. Substrate specificity studies with a series of 20 peptides SSCALX (where X indicates a naturally occurring amino acid) show that the recombinant enzyme behaves identically to the native enzyme and displays distinct specificity compared with mammalian protein farnesyltransferase. TB-PFT prefers Gln and Met at the X position but not Ser, Thr, or Cys, which are good substrates for mammalian protein farnesyltransferase. A structural homology model of the active site of TB-PFT provides a basis for understanding structure-activity relations among substrates and CAAX mimetic inhibitors.

Effects of rapid tryptophan depletion in patients with seasonal affective disorder in natural summer remission

BACKGROUND

Serotonergic mechanisms have been proposed for the pathophysiology of seasonal affective disorder (SAD) and the therapeutic effect of bright-light treatment. Previously, we showed that SAD patients, in clinical remission with light therapy during the winter, experienced transient depressive relapses after a rapid tryptophan depletion (RTD) technique, which results in decreased brain serotonin levels. The objective of this study was to investigate the effect of RTD in SAD patients who were in natural summer remission.

METHODS

Twelve drug-free patients with SAD by DSM-IV criteria and 10 normal subjects participated in this double-blind, placebo-controlled, crossover study. SAD patients were in natural summer remission for at least 8 weeks. Behavioural ratings and plasma tryptophan levels were obtained before, and 5 h after, ingesting an amino acid (AA) mixture +/- tryptophan. Experimental RTD and control sessions were scheduled 1 week apart.

RESULTS

The RTD session resulted in significant reduction in total and free plasma tryptophan levels compared to the control session. The behavioural data were analysed using repeated measures analysis of variance. This analysis found significant main effects of time (higher scores after AA ingestion) and diagnosis (higher scores in SAD patients), but no main effect of session or significant interaction effects between the three factors. Thus, there were no significant behavioural effects of RTD compared to the sham depletion control session.

CONCLUSIONS

The summer remission experienced by SAD patients is not dependent on plasma tryptophan levels (and presumably brain serotonin function) in the same manner as that of remission after light therapy. These results conflict with those of other laboratories, perhaps because of differences in study samples.

Expression of IGF system genes during T-antigen driven pituitary tumorigenesis

Expression of IGF-I, IGF-II, the Type-I IGF receptor and six IGF binding proteins were examined in three different T-ag-driven mouse tumors. Unlike the widespread expression of IGF-II in pancreatic beta-cell tumors, IGF-II was not widely expressed in the two different pituitary tumors examined indicating that a mechanism independent of focal IGF-II expression can also drive T-antigen tumorigenesis. In addition, multiple IGF binding proteins were expressed in all three tumor types. This expression, however, was generally heterogeneous with no specific changes to indicate a required role for any IGF binding protein in T-antigen tumorigenesis.

Examination of micro-tip reversed-phase liquid chromatographic extraction of peptide pools for mass spectrometric analysis

Mass spectrometry occupies a central position in most current protein identification schemes. So-called 'mass fingerprinting' techniques rely on composite mass patterns of proteolytic fragments, or dissociation products thereof, to query databases. Keys to successful analysis of ever smaller amounts are sensitivity and complete spectral information, both of which depend for a large part on proper sample preparation. Clean-up and concentration of peptide mixtures over eppendorf gel loading tips filled with chromatographic media (i.e. 'micro-tips') are believed to be quite useful in this regard. We have studied quantitative and qualitative aspects of polypeptide extraction using these small manual devices. Optimization of sample volume and additives, micro-tip bed volume, and eluent composition and volume, all contribute to effective recovery (approximately 65-70%, on average). Improper digest conditions can, in fact, lead to far bigger losses, suggesting the need for at least trace amounts of Zwittergent 3-16. Of particular interest is our finding that partial fractionation, obtained by two-step micro-tip elution, generally results in more and better signals during subsequent mass analysis. Thus, by using optimized micro-tips, in combination with adequate sample handling and instrumentation, direct mass spectrometric identification can be routinely and successfully done in any resource facility type setting.

Seasonality of symptoms in anorexia and bulimia nervosa

OBJECTIVE

Recent research has suggested that a large proportion of patients with bulimia nervosa have seasonal (winter) worsening of mood symptoms similar to seasonal affective disorder (SAD). The objectives of this study were to determine the specificity of this finding in anorexia and bulimia nervosa, and to further delineate the seasonal mood and eating patterns in bulimia nervosa.

METHOD

A modified Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to consecutive female patients assessed at an Eating Disorders Clinic with DSM-III-R diagnoses of bulimia nervosa (BN, N = 60) and anorexia nervosa (AN, N = 31), and to female nonclinical comparison subjects (NC, N = 50).

RESULTS

The BN group had higher global seasonality scores and more presumptive diagnoses of SAD than the other two groups; the AN patients, whether they had the restricting or binge eating/purging subtype, did not differ from the NC subjects. Thirty-two percent of the identified seasonal BN patients did not have parallel worsening of mood and eating symptoms in the same season.

DISCUSSION

These results suggest that seasonality of symptoms is specific to BN and that there may be separate mechanisms for the seasonality of mood and eating symptoms in some BN patients.

Effects of rapid tryptophan depletion in patients with seasonal affective disorder in remission after light therapy

BACKGROUND

Previous studies show that rapid tryptophan depletion reverses the effects of therapy with serotonergic, but not noradrenergic, antidepressant drugs in patients with remitted nonseasonal depression. The objective of this study was to investigate the effects of rapid tryptophan depletion in patients with seasonal affective disorder (SAD) that was in clinical remission after light therapy.

METHODS

Patients who met DSM-III-R criteria for recurrent major depressive episodes, seasonal (winter) pattern (equivalent to SAD), were treated with a standard course of light therapy. Ten patients with SAD in clinical remission after light therapy underwent rapid tryptophan depletion in a placebo-controlled, double-blind crossover study. Behavioral ratings and plasma tryptophan levels were obtained before and after rapid tryptophan depletion.

RESULTS

Plasma total and free tryptophan levels were significantly reduced to 20% of normal levels by the rapid tryptophan depletion. The depletion session resulted in significant increases in depression scores compared with the sham control session. Six of 10 patients had a clinically significant relapse of their depression following the tryptophan depletion session.

CONCLUSIONS

Rapid tryptophan depletion appears to reverse the antidepressant effect of bright light therapy in patients with SAD. This suggests that the therapeutic effects of bright light in SAD may involve a serotonergic mechanism.

Genetic ablation of IGFBP-2 suggests functional redundancy in the IGFBP family

Gene targeting allows mutations to be introduced selectively into any mouse locus of interest. This approach has already been used to demonstrate that insulin-like growth factor (IGF) peptides and receptors are required in vivo for normal prenatal growth. One of the IGFBP genes, IGFBP-2, has also been disrupted using gene targeting, and homozgyous null BP-2 mice are characterized by a decreased spleen size most apparent during early postnatal stages and increased adult circulating levels of several other IGFBPs. These alterations are considered less dramatic than the phenotypes initially predicted based on the fetal IGFBP-2 expression pattern, although several physiological paradigms can be envisioned that will provide additional tests for specific aspects of IGFBP function. Since all six IGFBP genes are expressed during prenatal rodent development, as well as in adult tissues, the IGFBP-2 null phenotype must also be compared with genetic ablations involving members of other gene families and in the context of the other IGFBP expression patterns in rodent embryonic, extraembryonic, and uterine tissues.

Tissue-specific expression of the insulin-like growth factor binding protein (IGFBP) mRNAs in mouse and rat development

The insulin-like growth factor binding proteins (IGFBPs) are polypeptides which are thought to modulate the bioactivity of IGF-I and IGF-II, and may also have activities independent of the IGFs. The expression patterns of IGFBPs-1, -3, -4, and -6 in midgestational rodents were analyzed using in situ hybridization to begin to characterize the role of these IGFBPs during development. All IGFBPs are expressed at least as early as rat embryonic day 14 (e14), and each has a unique pattern of expression. IGFBP-1 mRNA is expressed by the liver throughout mid and late gestation. IGFBP-3 mRNA is expressed at high levels in the urogenital tract, several muscle groups, and the nasal epithelia. IGFBP-3 transcripts are also expressed at lower levels by many non-neural tissue types, including the liver, stomach, and heart. IGFBP-4 is abundantly expressed by many tissues in the developing embryo, with the notable exceptions of the spinal cord, specific cartilage groups, and the thymic cortex. IGFBP-6 is expressed in the liver by e14, and also by a previously unrecognized cell population surrounding developing cartilage. Taken together these observations suggest distinct roles in development for each of the IGFBPs.

Beta-alanine induced ion channels in the membrane of cultured spinal cord neurons

beta-Alanine (beta-ALa) is a structural analog of the putative inhibitory transmitters gamma-aminobutyric acid (GABA) and glycine. beta-ALa itself depresses firing in cultured mouse spinal cord (SC) neurons, by selectively increasing membrane conductance to chloride ions. Patch clamp recordings now reveal that beta-ALa-sensitive chloride channels in SC cells can open to at least 5 conductance states, 4 of which are very similar to states seen when GABA or glycine is applied to these cells. However, a large, 80 pS conductance state is activated at detectable frequency only in the presence of beta-ALa itself.

Membrane channels activated by taurine in cultured mouse spinal cord neurons

Patch-clamp methods were used to compare biophysical properties of anion channels activated by taurine and gamma-aminobutyric acid in the membrane of cultured mouse spinal neurons. Outside-out patches were voltage clamped at -80 mV at a temperature of 21-23 degrees C. Bath application of GABA (1.5-2 microM) or taurine (5-40 microM) induced chloride-dependent single-channel currents in 14/20 patches tested. Amplitude distributions of these currents showed peaks corresponding to conductance levels of 8, 16, 27 and 46 pS. Only a few percent of GABA-induced events reached the 46 pS level, while 30% of taurine-induced currents were of this size. The average lifetime of taurine-activated channels in the open state was 1.0 +/- 0.07 ms, significantly shorter than the corresponding value for GABA (1.6 +/- 0.08 ms). Taurine-induced currents were abolished by 10 microM strychnine, but persisted in the presence of 50 microM bicuculline.

An association between encephalomyocarditis virus infection and reproductive failure in pigs

An outbreak of reproductive failure, characterised by mummified foetuses and stillbirths, was investigated in an intensive piggery. Six foetuses that died towards the end of gestation had multifocal myocardial necrosis and encephalomyocarditis virus was recovered from 4 of these foetuses but not from 6 mummified foetuses. There was also a significant increase in failure of conception or early embryonic deaths in sows mated at the same time as sows which produced affected litters.