Long-term results of digital arthrodesis with the Harrison-Nicolle peg

This study determined the long-term success of digital arthrodesis with the Harrison-Nicolle peg. We reviewed 90 digital joints in 60 patients fused with the peg between 1986 and 1998 at a mean follow-up of 6 (range 2-11) years. The prime indication for surgery was rheumatoid arthritis. The early complication rate was 8%. At 1 month 89% of joints were pain-free and stable. In the long-term follow up, 96% of the joints were pain-free and stable, with the original angle of fusion. 85% achieved bony fusion, with no clinical difference between bony and fibrous fusion. Overall there was a significantly higher complication rate in the distal interphalangeal joint. We conclude that, with the exception of the distal interphalangeal joint, the Harrison-Nicolle peg is extremely effective for digital arthrodesis in the rheumatoid patient.

A systematic approach to provider based disability management

Tacit within the treatment goals of every workers' compensation case is timely return of the worker to pre-injury status. Assigned disability status must truly reflect the extent of medical impairment and functional limitations affecting return to his/her customary job. Permanent Partial Disability (PPD) awards with associated legal involvement are widely acknowledged as a major cost driver within the Workers' Compensation system. Medical providers are encouraged to become pro-active disability management specialists for each workers' compensation case. Provider review of critical process checkpoints and integration of medical treatment with disability guidelines maximize benefits to the injured employee and the employer. This in turn enhances providers' control of patient care with less emphasis on external case managers.

Mitochondrial modulation of calcium signaling at the initiation of development

Fertilization triggers cytosolic Ca(2+) oscillations that activate mammalian eggs and initiate development. Extensive evidence demonstrates that Ca(2+) is released from endoplasmic reticulum stores; however, less is known about how the increased Ca(2+) is restored to its resting level, forming the Ca(2+) oscillations. We investigated whether mitochondria also play a role in activation-associated Ca(2+) signaling. Mitochondrial dysfunction induced by the mitochondrial uncoupler FCCP or antimycin A disrupted cytosolic Ca(2+) oscillations, resulting in sustained increase in cytosolic Ca(2+), followed by apoptotic cell death. This suggests that functional mitochondria may participate in sequestering the released Ca(2+), contributing to cytosolic Ca(2+) oscillations and preventing cell death. By centrifugation, mouse eggs were stratified and separated into fractions containing both endoplasmic reticulum and mitochondria and fractions containing endoplasmic reticulum with no mitochondria. The former showed Ca(2+) oscillations by activation, whereas the latter exhibited sustained elevation in cytosolic Ca(2+) but no Ca(2+) oscillations, suggesting that mitochondria take up released cytosolic Ca(2+). Further, using Rhod-2 for detection of mitochondrial Ca(2+), we found that mitochondria exhibited Ca(2+) oscillations, the frequency of which was not different from that of cytosolic Ca(2+) oscillations, indicating that mitochondria are involved in Ca(2+) signaling during egg activation. Therefore, we propose that mitochondria play a crucial role in Ca(2+) signaling that mediates egg activation and development, and apoptotic cell death.

Reversal of chloroquine resistance in Plasmodium falciparum using combinations of chemosensitizers

Research into chloroquine resistance reversal in Plasmodium falciparum has revealed a widespread range of functionally and structurally diverse chemosensitizers. However, nearly all of these chemosensitizers reverse resistance optimally only at concentrations that are toxic to humans. Verapamil, desipramine, and trifluoperazine were shown to potentiate chloroquine accumulation in a chloroquine-resistant (CQ(r)) strain of P. falciparum, while progesterone, ivermectin, and cyclosporin A were not shown to potentiate chloroquine accumulation. The simultaneous use of two or even three of these chemosensitizers at concentrations within their therapeutic ranges in humans displayed an additive effect in potentiating chloroquine accumulation in the CQ(r) strain. The levels of resistance reversal achieved with these multiple combinations were comparable to those achieved with high concentrations of the single agents used to enhance the activity of chloroquine. No chemosensitizer, whether used singly or in combination, potentiated any change in chloroquine accumulation or a shift in the 50% inhibitory concentration for the chloroquine-sensitive strain. The use of combinations of chemosensitizers at concentrations not toxic to humans could effectively reverse chloroquine resistance without the marked toxicity from the use of a single agent at high concentrations. This cocktail of chemosensitizers may serve as a viable treatment to restore the efficacy of chloroquine in patients with malaria.

Compensating for provider nonresponse using response propensities to form adjustment cells: the National Immunization Survey

OBJECTIVES

The National Immunization Survey (NIS) uses two phases of data collection to obtain vaccination information from a sample of young children: a random-digit-dialing (RDD) survey for identifying households with children 19-35 months of age, followed by a mail survey for obtaining provider-reported vaccination histories about these children. Provider-reported vaccination histories are used to estimate vaccination coverage rates. In 1998, provider-reported vaccination histories were not obtained for 32.9% of children with a completed RDD interview. This report describes the statistical methods adopted in 1998 to reduce the bias in vaccination coverage estimates that could result from "vaccination history nonresponse," that is, differences between children for whom provider data was obtained and those for whom it was not obtained.

METHODS

In the methods adopted in 1998, children with completed NIS RDD interviews are grouped into adjustment cells defined by their propensity to have adequate provider data. Sampling weights of children with adequate provider data are divided by the cell-specific weighted response rate to allow these children to represent all children in the cell.

RESULTS

Using an "optimal" number of cells, the overall extent of bias reduction was 0.5%, suggesting that provider nonresponse bias was small. Authoritative literature suggests using five cells. No statistically significant differences were observed in vaccination coverage estimates when comparing estimates based on the "optimal" number of cells with five cells. Thus, five adjustment cells are used to reduce provider nonresponse bias in the NIS vaccination coverage estimates. No substantively important differences were observed between estimates based on the methodology used prior to 1998 and the methodology adopted in 1998.

Nuclear post-transcriptional control of gene expression

The mammalian nucleus has considerable control over nascent transcripts. The basic mechanisms of post-transcriptional processing are well understood and recently some of the principles underlying the regulation of nuclear processing events have been elucidated. Here we review the recent progress in identification of signalling pathways that modulate the action of key RNA-binding proteins which regulate splicing, and the mechanisms of action of the C-terminal domain of RNA polymerase II that co-ordinate transcription with nuclear mRNA processing events.

Telomeric sequences, radiation sensitivity and genomic instability

PURPOSE

To review the basic features of telomeres with particular emphasis on their potential importance in radiation biology. Recent findings suggest that telomere length can influence radiation sensitivity in mouse and that several human radiosensitive disorders also show abnormalities in telomere dynamics. Numerous studies indicate that telomeric sequences may play a role in determining the stability of certain genomic regions both spontaneously and following irradiation. Furthermore, a number of transmissible genomic instability systems have been described in which it appears that telomere metabolism may be contributing to the delayed effects observed. Features of telomeres and telomere biology relevant to these topics are reviewed.

CONCLUSIONS

The evidence that telomeres and the molecular pathways of telomere maintenance can play a role in determining the outcome of radiation exposure is now substantial. Thus, the field of telomere biology deserves continued attention from radiobiologists.

Proteins and lipids define the diffusional field of nitric oxide

Nitric oxide (NO) fluxes released from the surface of individual activated macrophages or cells localized in small aggregates were measured with a novel polarographic self-referencing microsensor. NO fluxes could be detected at distances from the cells of 100-500 microm. The initial flux and the distance from the cells at which NO could be detected were directly related to the number of cells in the immediate vicinity of the probe releasing NO. Thus, whereas NO fluxes of approximately 1 pmol. cm(-2). s(-1) were measured from individual macrophages, aggregates composed of groups of cells varying in number from 18 to 48 cells produced NO fluxes of between approximately 4 and 10 pmol. cm(-2). s(-1). NO fluxes required the presence of L-arginine. Signals were significantly reduced by the addition of hemoglobin and by N-nitro-L-arginine methyl ester. NO fluxes were greatest when the sensor was placed immediately adjacent to cell membranes and declined as the distance from the cell increased. The NO signal was markedly reduced in the presence of the protein albumin but not by either oxidized or reduced glutathione. A reduction in the NO signal was also noted after the addition of lipid micelles to the culture medium. These results demonstrate that NO can be detected at significant distances from the cell of origin. In addition, both proteins and lipids strongly influence the net movement of free NO from macrophages. This suggests that these tissue components play an important role in regulating the biological activity of NO.

Anandamide induces cardiovascular and respiratory reflexes via vasosensory nerves in the anaesthetized rat

1. We tested the hypothesis that sensory nerves innervating blood vessels play a role in the local and systemic regulation of the cardiovascular and respiratory (CVR) systems. We measured CVR reflexes evoked by administration of anandamide (86 - 863 nmoles) and capsaicin (0.3 - 10 nmoles) into the hindlimb vasculature of anaesthetized rats. 2. Anandamide and capsaicin each caused a rapid dose-dependent reflex fall in blood pressure and an increase in ventilation when injected intra-arterially into the hindlimb. 3. Action of both agonists at the vanilloid receptor (VR1) on perivascular sensory nerves was investigated using capsazepine (1 mg kg(-1) i.a.) a competitive VR1 antagonist, ruthenium red (1 mg kg(-1) i.a.), a non-competitive antagonist at VR1, or a desensitizing dose of capsaicin (200 nmoles i.a.). The cannabinoid receptor antagonist SR141716 (1 mg kg(-1) i.a.) was used to determine agonist activity at the CB(1) receptor. 4. Capsazepine, ruthenium red, or acute VR1 desensitization by capsaicin-pretreatment, markedly attenuated the reflex CVR responses evoked by anandamide and capsaicin (P< 0.05; paired Student's t-test). Blockade of CB(1) had no significant effect on the responses to anandamide. 5. Local sectioning of the femoral and sciatic nerves attenuated CVR responses to anandamide and capsaicin (P< 0.05). Vagotomy or carotid sinus sectioning had no significant effect on anandamide- or capsaicin-induced responses. 6. These data demonstrate that both the endogenous cannabinoid, anandamide, and the vanilloid, capsaicin, evoke CVR reflexes when injected intra-arterially into the rat hindlimb. These responses appear to be mediated reflexly via VR1 located on sensory nerve endings within the hindlimb vasculature.

Use of phosphoimidazolide-activated guanosine to investigate the nucleophilicity of spermine and spermidine

Guanosine 5'-phosphate 2-methylimidazolide (2-MeImpG), a labile phosphoimidazolide analog of guanosine triphosphate, was used to test the reactivity of the natural polyamines (PAs), spermine (spm) and spermidine (spd). The products are the guanosine 5'-phosphate-polyamine derivatives (PA-pG: spd-pG and spm-pG) which are quite stable in the range 4 < pH < 11. Our study is the first of which we are aware that reports on the nucleophilicity of these amines. The main findings are as follows. (i) HPLC analysis of the products indicates the formation of only two of the three possible spd products and only one of the two possible spm products. These results can be explained if only the primary amino groups of the two polyamines are reactive, while the secondary amino groups are rendered unreactive by a steric effect. The reactions of 2-MeImpG and other phosphoimidazolide derivatives of nucleosides (ImpNs) with primary and secondary monoamines support this interpretation (Kanavarioti et al. J. Org. Chem. 1995, 60, 632). (ii) The product ratio of the two spd-pG adducts derived from the primary amino groups varies between 2.40 and 0.71 in the range 6.1 < or equal to pH < or equal to 11.9. Such small variation in the product ratio can only be rationalized by the similar, but not identical, basicity of the two primary amino groups and provides strong support for a previously reported model for polyamine ionization (Onasch et. al. Biophys. Chem. 1984, 19, 245). (iii) On the basis of our kinetic determinations conditions at which the nucleophilicity of these amines is at a minimum and at which other interactions with ImpNs could be tested can be chosen.

Suppression of granulocyte-macrophage colony-stimulating factor expression by glucocorticoids involves inhibition of enhancer function by the glucocorticoid receptor binding to composite NF-AT/activator protein-1 elements

Increased expression of a number of cytokines including GM-CSF is associated with chronic inflammatory conditions such as bronchial asthma. Glucocorticoid therapy results in suppression of cytokine levels by a mechanism(s) not yet fully understood. We have examined regulation of GM-CSF expression by the synthetic glucocorticoid dexamethasone in human T cells. Transient transfection assays with reporter constructs revealed that dexamethasone inhibited the function of the GM-CSF enhancer, but had no effect on regulation of GM-CSF expression occurring through the proximal promoter. Activation of the GM-CSF enhancer involves cooperative interaction between the transcription factors NF-AT and AP-1. We demonstrate here that glucocorticoid-mediated inhibition of enhancer function involves glucocorticoid receptor (GR) binding to the NF-AT/AP-1 sites. These elements, which do not constitute recognizable glucocorticoid response elements, support binding of the GR, primarily as a dimer. This binding correlates with the ability of dexamethasone to inhibit enhancer activity of the NF-AT/AP-1 elements, suggesting a competition between NF-AT/AP-1 proteins and GR.

The potential use of urinary excretion data for assessing the relative bioavailability of rifampicin in fixed dose combination anti-tuberculosis formulations

SETTING

The perceived need for simple, non-invasive methods of assessing the relative bioavailability of rifampicin in fixed-dose combination (FDC) anti-tuberculosis formulations.

OBJECTIVE

To compare the performance of methods based on urinary excretion data with those utilising plasma concentration-time profiles to assess the relative bioavailability of rifampicin in combined and single-drug formulations.

DESIGN

A two-period randomised crossover bioequivalence study in healthy male volunteers with a 1 week washout period between treatments. Plasma rifampicin concentrations were measured at 0, 1, 2, 4, 6 and 8 hours after each drug administration using a high performance liquid chromatography (HPLC) method. The rifampicin and desacetylrifampicin content of complete urinary collections made from 0-4 and 4-8 hours after dosage were determined using both the HPLC and a much simpler colorimetric procedure.

RESULTS

There was good agreement between the relative bioavailability of the formulations using plasma and urinary excretion data, although the precision of the urinary-based estimates was slightly less than those derived from the plasma findings. There was also good agreement between the HPLC and colorimetric estimates of the combined urinary excretion of rifampicin plus desacetylrifampicin.

CONCLUSIONS

Urinary excretion data may be used for ongoing quality control to confirm that commercial combined rifampicin-containing formulations that were initially shown to be satisfactory continue to be so.

Identification and characterization of the STIM (stromal interaction molecule) gene family: coding for a novel class of transmembrane proteins

STIM1 (where STIM is stromal interaction molecule) is a candidate tumour suppressor gene that maps to human chromosome 11p15.5, a region implicated in a variety of cancers, particularly embryonal rhabdomyosarcoma. STIM1 codes for a transmembrane phosphoprotein whose structure is unrelated to that of any other known proteins. The precise pathway by which STIM1 regulates cell growth is not known. In the present study we screened gene databases for STIM1-related sequences, and have identified and characterized cDNA sequences representing a single gene in humans and other vertebrates, which we have called STIM2. We identified a single STIM homologue in Drosophila melanogaster (D-Stim) and Caenorhabditis elegans, but no homologues in yeast. STIM1, STIM2 and D-Stim have a conserved genomic organization, indicating that the vertebrate family of two STIM genes most probably arose from a single ancestral gene. The three STIM proteins each contain a single SAM (sterile alpha-motif) domain and an unpaired EF hand within the highly conserved extracellular region, and have coiled-coil domains that are conserved in structure and position within the cytoplasmic region. However, the STIM proteins diverge significantly within the C-terminal half of the cytoplasmic domain. Differential levels of phosphorylation appear to account for two molecular mass isoforms (105 and 115 kDa) of STIM2. We demonstrate by mutation analysis and protein sequencing that human STIM2 initiates translation exclusively from a non-AUG start site in vivo. STIM2 is expressed ubiquitously in cell lines, and co-precipitates with STIM1 from cell lysates. This association into oligomers in vivo indicates a possible functional interaction between STIM1 and STIM2. The structural similarities between STIM1, STIM2 and D-STIM suggest conserved biological functions.

Development and application of a self-referencing glucose microsensor for the measurement of glucose consumption by pancreatic beta-cells

Glucose gradients generated by an artificial source and beta-cells were measured using an enzyme-based glucose microsensor, 8-microm tip diameter, as a self-referencing electrode. The technique is based on a difference measurement between two locations in a gradient and thus allows us to obtain real-time flux values with minimal impact of sensor drift or noise. Flux values were derived by incorporation of the measured differential current into Fick's first equation. In an artificial glucose gradient, a flux detection limit of 8.2 +/- 0.4 pmol.cm(-2).s(-1) (mean +/- SEM, n = 7) with a sensor sensitivity of 7.0 +/- 0.4 pA/ mM (mean +/- SEM, n = 16) was demonstrated. Under biological conditions, the glucose sensor showed no oxygen dependence with 5 mM glucose in the bulk medium. The addition of catalase to the bulk medium was shown to ameliorate surface-dependent flux distortion close to specimens, suggesting an underlying local accumulation of hydrogen peroxide. Glucose flux from beta-cell clusters, measured in the presence of 5 mM glucose, was 61.7 +/- 9.5 fmol.nL(-1).s(-1) (mean +/- SEM, n = 9) and could be pharmacologically modulated. Glucose consumption in response to FCCP (1 microM) transiently increased, subsequently decreasing to below basal by 93 +/- 16 and 56 +/- 6%, respectively (mean +/- SEM, n = 5). Consumption was decreased after the application of 10 microM rotenone by 74 +/- 5% (mean +/- SEM, n = 4). These results demonstrate that an enzyme-based amperometric microsensor can be applied in the self-referencing mode. Further, in obtaining glucose flux measurements from small clusters of cells, these are the first recordings of the real-time dynamic of glucose movements in a biological microenvironment.

Minimal amidine structure for inhibition of nitric oxide biosynthesis 2 2Abbreviations: NOS1, neuronal nitric oxide synthase; NOS2, inducible nitric oxide synthase; l-NMMA, NG-monomethyl-l-arginine; and NIO, l-N5-(iminoethyl)ornithine

Pharmacological modulation of nitric oxide synthase activity has been achieved using structural analogs of arginine. In the present studies, we demonstrated that the minimal amidine structure required for enzymatic inhibition is formamidine. We found that the production of nitric oxide by primary cultures of rat hepatocytes and several mouse and human cell lines, including RAW 264.7 macrophages, PAM 212 keratinocytes, G8 myoblasts, S180 sarcoma, CX-1 human colon cells, and GH3 rat pituitary cells, was inhibited in a concentration- and time-dependent manner by formamidine. Formamidine was 2- to 6-fold more effective in inhibiting nitric oxide production in cells expressing inducible nitric oxide synthase (NOS2) than in a cell line expressing calcium-dependent neuronal nitric oxide synthase (NOS1). Whereas formamidine had no effect on gamma-interferon-induced expression of nitric oxide synthase protein, its enzymatic activity was blocked. Kinetic analysis revealed that formamidine acts as a simple competitive inhibitor with respect to arginine (K(i) formamidine approximately 800 microM). Using a polarographic microsensor to measure real-time flux of nitric oxide release from RAW 264.7 macrophages, formamidine was found to require 30-90 min to inhibit enzyme activity, suggesting that cellular uptake of the drug may limit its biological activity. Our data indicate that formamidine is an effective inhibitor of nitric oxide production. Furthermore, its low toxicity may make it useful as a potential therapeutic agent in diseases associated with the increased production of nitric oxide.

Vaccination status of children living in rural areas in the United States: are they protected?

OBJECTIVE

To estimate the vaccination coverage levels of children living in rural areas and identify statistically significant differences in coverage between children living in rural areas and their suburban and urban counterparts.

METHODS

Children aged 19 to 35 months participating in the 1999 National Immunization Survey (NIS) were included in the study. Children were classified as living in a rural, urban, or suburban area based on their telephone exchange (area code plus the first three digits of the telephone number). Statistically significant differences in vaccination coverage levels between the rural population and their urban counterparts were determined for individual vaccines and vaccine series.

RESULTS

Overall, 18% of the children included in the 1999 NIS lived in a rural area, 46% lived in a suburban area, and 36% lived in an urban area. The characteristics of the rural population were: 72% were white, non-Hispanic; 24% were below the poverty level; 16% had a mother with <12 years of education; and 30% received vaccinations from a public provider. Eighty percent of rural children, 79% of suburban children, and 77% of urban children completed the 4:3:1:3 series. The rural population had statistically significantly lower (p<0.01) varicella coverage levels than their suburban and urban counterparts.

CONCLUSION

Results of this study suggest that children living in rural areas are just as likely to receive the basic 4:3:1:3 vaccination series as their suburban and urban counterparts. Uptake of the varicella vaccine appears to be slower in rural areas than urban areas. Further studies are recommended to identify the risk factors for not receiving the varicella vaccine in rural areas.

Vaccination status of children in the Women, Infants, and Children (WIC) Program: are we doing enough to improve coverage?

BACKGROUND

Vaccination-promoting strategies in the Supplemental Nutrition Program for Women, Infants, and Children (WIC) have been shown to produce dramatic improvements in coverage and other health outcomes.

OBJECTIVES

To determine national and state-specific population-based vaccine coverage rates among preschool children who participate in the WIC program, and to describe the strategies for promoting vaccination in WIC.

DESIGN/METHODS

Demographic data, WIC participation, and vaccination histories for children aged 24 to 35 months in 1999 were collected from parents through the National Immunization Survey. The healthcare providers for the children in the survey were contacted to verify and complete vaccination information. We defined children as up-to-date (UTD) if they had received four doses of diphtheria and tetanus toxoids and pertussis vaccine (DPT), three doses of poliovirus vaccine, one dose of measles-mumps-rubella vaccine (MMR), and three doses of Haemophilus influenzae type b vaccine (Hib) by 24 months. Description of state-level vaccination-promoting activities in WIC was collected through an annual survey completed by the state WIC and immunization program directors.

RESULTS

Complete data were collected on 15,766 children, of whom 7783 (49%) participated in WIC sometime in their lives. Nationally, children who had ever participated in WIC were less well-immunized at 24 months compared to children who had not: 72.9% UTD (95% CI, 71.3-74.5) versus 80.8% UTD (95% CI, 79.5-82.1), respectively. In 42 states, 24-month coverage among WIC participants was less than among non-WIC participants, including 13 states where the difference was > or = 10%. Vaccination activities linked with WIC were reported from 76% of 8287 WIC sites nationwide. States conducting more-frequent interventions and reaching a higher proportion of WIC participants had 40% higher vaccination coverage levels for the WIC participants in that state (p<0.05).

CONCLUSIONS

Children served by WIC remain less well-immunized than the nation's more-affluent children who do not participate in WIC. Thus, WIC remains a good place to target these children. This study provides evidence that fully implemented WIC linkage works to improve vaccination rates. Strategies that have been shown to improve the vaccination coverage levels of WIC participants should be expanded and adequately funded to protect these children.

Overview of the sampling design and statistical methods used in the National Immunization Survey

Abstract: The National Immunization Survey (NIS) is a large federally funded survey designed to estimate vaccination coverage rates for children residing in the United States aged 19 to 35 months. In 1999, over 8 million telephone call attempts were made to obtain provider-reported vaccination histories on 22,521 children in the age range of interest.

Differential sensitivity to etoposide (VP-16)-induced S phase delay in a panel of small-cell lung carcinoma cell lines with G1/S phase checkpoint dysfunction

PURPOSE

The highly schedule-dependent cytotoxic agent etoposide (VP-16) is initially effective in the treatment of small-cell lung cancer (SCLC), particularly in multidrug combination chemotherapy. Heterogeneity in cellular sensitivity to cell cycle arrest may underpin the inadequacy of low-dose extended-cycle single-agent regimes in tumours with partially dysfunctional apoptotic signalling pathways. We have studied the longevity and dose dependency of cell cycle and to a limited extent the apoptotic responses of a panel of seven unselected SCLC cell lines, screened for TP53 status.

METHODS

Cells were analysed using flow cytometry for the cell cycle responses and field inversion gel electrophoresis for apoptotic patterns. The mitotic inhibitor nocodazole was used to assess and correct cell line response data for differences in cell cycle traverse per se.

RESULTS

An overall lack of G1/S arrest and muted DNA fragmentation were consistent with the presence of TP53 gene abnormalities. Maximal G2 arrest but with clear recovery potential occurred at an exposure dose (ED, concentration of drug x time) value of approximately 24 microM h. Higher doses (ED values >48 microM h) revealed a wide variation in S phase delay that was independent of population doubling time and could not be compensated for by drug concentration changes alone.

CONCLUSION

The results suggest that heterogeneity in the in vitro sensitivity of unselected SCLC cell lines to S phase arrest is demonstrable at ED values projected to be critical for clinical activity. Such variation in S phase responsiveness may reflect differences in checkpoint activation and offer a functional target for the design of more-effective combination therapy.

In situ analysis of pH gradients in mosquito larvae using non-invasive, self-referencing, pH-sensitive microelectrodes

The alkaline environment, pH approximately 11, in the anterior midgut lumen of mosquito larvae is essential for normal nutrition and development. The mechanism of alkalization is, however, unknown. Although evidence from immunohistochemistry, electron microscopy and electrophysiology suggests that a V-ATPase is present in the basal membranes of the epithelial cells, its physiological role in the alkalization process has not been demonstrated. To investigate a possible role of the V-ATPase in lumen alkalization, pH gradients emanating from the hemolymph side of the midgut in semi-intact mosquito larvae were measured using non-invasive, self-referencing, ion-selective microelectrodes (SERIS). Large H+ concentration gradients, with highest concentrations close to the basal membrane (outward [H+] gradients), were found in the anterior midgut, whereas much smaller gradients, with concentrations lowest close to this membrane (inward [H+] gradients), were found in the gastric caeca and posterior midgut. Similar region-specific pH gradients, with consistent anterior-to-posterior profiles, were observed in individuals of two Aedes species, Aedes aegypti from semi-tropical Florida and Aedes canadensis from north-temperate Massachusetts. The gradients remained in a steady state for up to 6 h, the maximum duration of the recordings. Bafilomycin A1 (10(−5), 10(−7)mol × l(−1)) on the hemolymph side greatly diminished the [H+] gradients in the anterior midgut but had no effect on the gradients in the gastric caecum and posterior midgut. These physiological data are consistent with the previous findings noted above. Together, they support the hypothesis that a basal, electrogenic H+ V-ATPase energizes luminal alkalization in the anterior midgut of larval mosquitoes.

Polydactyly of the feet in children: suggestions for surgical management

Polydactyly is the commonest congenital deformity of the foot, presenting as a range of defects from minor soft tissue duplications to major bony abnormalities. There is a relative paucity of information on the management of this condition in the literature compared to that concerning polydactyly of the hand. We present a consecutive series of 34 cases of polydactyly of the foot in 25 patients treated surgically at our unit and these are classified according to the protocol described by Blauth and Olason. We emphasise the importance of preoperative classification using radiographs and an individualised surgical approach giving consideration to aesthetic and functional outcome. In the literature a number of authors have expressed the view that in polydactyly of the fifth ray of the foot the most lateral digit should always be excised irrespective of whether this is the more fully formed digit. We believe this should not always be the case and we describe two cases of polysyndactyly where the more medial element of a fifth-ray polydactyly was excised to allow for better maintenance of the contour of the foot. This involved more complex surgery than excision of the lateral element but gave a superior cosmetic and functional result.