Primary vulvar melanoma in an adolescent patient

Herein we describe the case of a Black adolescent who was found to have widely metastatic melanoma originating from a primary vulvar lesion. The lesion presented as a pink, vegetative nodule of the clitoral hood which grew in size over several years and was confirmed to be melanoma on shave biopsy. This patient's amelanotic presentation in conjunction with the rare incidence of vulvar melanoma contributed to the delay in diagnosis. This case exemplifies the challenge of early recognition of potentially malignant vulvar lesions for primary care providers in adolescents.

Abstract 309: Small-molecule PDE4 Activators Limit Isoproterenol-induced Hypertrophy in Rat Neonatal Cardiomyocytes

Increasing the cellular levels of the second messenger cAMP, such as via activation of β-adrenergic receptors (βARs), is the most powerful mechanism to acutely increase cardiac output. However, chronic βAR stimulation predisposes to the development of heart failure (HF) by promoting arrhythmias and pathologic cardiac hypertrophy. Cardiac myocyte cAMP levels are tightly regulated by cyclic nucleotide phosphodiesterases (PDEs), a family of isoenzymes that hydrolyze and inactivate cAMP. Prior studies have shown that development of HF is associated with a downregulation of the expression and activity of Type 4 PDEs (PDE4s) in humans and animals. We propose that this reduction in PDE4 is maladaptive and may contribute to the development of HF, because genetic or pharmacologic inactivation of PDE4s is associated with an increased propensity to arrhythmias and development of pathologic cardiac hypertrophy. We propose that, conversely, an increase in PDE4 protein and/or activity would be cardioprotective. To test this hypothesis, we have utilized rat neonatal cardiomyocytes (RNCM) in culture as a model system. Long term treatment with Isoproterenol (Iso) induces hypertrophy in these cells as reflected by increased cell surface/size. To stimulate PDE4 activity, which contributes about 50% of the total cAMP-PDE activity in RNCMs, cells were treated with small-molecule PDE4 activators, which we recently identified in a high throughout screen. We find that small-molecule PDE4 activators reduce Iso-induced cellular cAMP levels as measured by enzyme immuno assay and suppress Iso-induced PKA signaling, such as the PKA-mediated phosphorylation of phospholamban. Moreover, treatment with PDE4 activators alleviates the Iso-dependent increase in cell size in RNCM indicating that pharmacologic PDE4 activation can serve to limit cardiomyocyte hypertrophy.

Impedance spectroscopy for monosaccharides detection using responsive hydrogel modified paper-based electrodes

Novel paper-based impedance sensor for saccharide sensing in the sub-mM range.

Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications

The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes.

Prenatal betamethasone does not affect glutamatergic or GABAergic neurogenesis in preterm newborns

Prenatal glucocorticoids (GCs) are routinely used for pregnant women in preterm labor to prevent respiratory distress syndrome and intraventricular hemorrhage in premature infants. However, the effect of antenatal GCs on neurogenesis in preterm neonates remains elusive. Herein, we hypothesized that prenatal GCs might suppress both glutamatergic and GABAergic neurogenesis in preterm rabbits and that this treatment would induce distinct changes in the expression of transcription factors regulating these developmental events. To test our hypotheses, we treated pregnant rabbits with betamethasone at E27 and E28, delivered the pups at E29 (term=32d), and assessed neurogenesis at birth and postnatal day 3. We quantified radial glia (Sox2(+)) and intermediate progenitor cells (Tbr2(+)) in the dorsal cortical subventricular zone to assess glutamatergic neuronal progenitors, and counted Nkx2.1(+) and Dlx2(+) cells in the ganglionic eminence to evaluate GABAergic neurogenesis. In addition, we assayed transcription factors regulating neurogenesis. We found that prenatal GCs did not affect the densities of radial glia and intermediate progenitors of glutamatergic or GABAergic neurons. The number of GABA(+) interneurons in the ganglionic eminence was similar between the prenatal GC-treated pups compared to untreated controls. Moreover, the mRNA expression of transcription factors, including Pax6, Ngn1/2, Emx1/2, Insm1, Dlx1, Nkx2.1, and Gsh2, were comparable between the two groups. However, there was a transient elevation in Mash1 protein in betamethasone-treated pups relative to controls at birth. These data suggest that prenatal GC treatment does not significantly impact the balance of glutamatergic and GABAergic neurogenesis in premature infants.

Validation of a fully autonomous phosphate analyser based on a microfluidic lab-on-a-chip

This work describes the design of a phosphate analyser that utilises a microfluidic lab-on-a-chip. The analyser contains all the required chemical storage, pumping and electronic components to carry out a complete phosphate assay. The system is self-calibrating and self-cleaning, thus capable of long-term operation. This was proven by a bench top calibration of the analyser using standard solutions and also by comparing the analyser's performance to a commercially available phosphate monitor installed at a waste water treatment plant. The output of the microfluidic lab-on-a-chip analyser was shown to have sensitivity and linear range equivalent to the commercially available monitor and also the ability to operate over an extended period of time.

Blueberry supplementation enhances signaling and prevents behavioral deficits in an Alzheimer disease model

Previously, we showed that blueberry (BB) supplementation reversed the deleterious effects of aging on motor behavior and neuronal signaling in senescent rodents. We now report that BB-fed (from 4 months of age) APP + PS1 transgenic mice showed no deficits in Y-maze performance (at 12 months of age) with no alterations in amyloid beta burden. It appeared that the protective mechanisms are derived from BB-induced enhancement of memory-associated neuronal signaling (e.g. extracellular signal-regulated kinase) and alterations in neutral sphingomyelin-specific phospholipase C activity. Thus, our data indicate for the first time that it may be possible to overcome genetic predispositions to Alzheimer disease through diet.

Enantioselective molecular sensing of aromatic amines using tetra-(S)-di-2-naphthylprolinol calix[4]arene

This paper presents new analytical data, and evidence of the fluorescence quenching mechanism involved in enantioselective signals obtained with the chiral host tetra-(S)-di-2-naphthylprolinol calix[4]arene. Excellent selectivity is obtained with phenylglycinol and norephidrine in methanol, and samples of unknown enantiomeric composition have been determined with an average error of 1.08 and 0.62%, respectively (n = 6), on the basis of a single fluorescence measurement. The absence of any quenching observed with the related amines of phenylalaninol is attributed to a methylene spacer which inhibits efficient interaction between the aryl group of the guest and the naphthyl group of the host. The importance of the phenyl group of the guest in the quenching mechanism is confirmed by the complete absence of any quenching effect with cyclohexylethylamine.

Point-of-need diagnosis of cystic fibrosis using a potentiometric ion-selective electrode array

The novel approach of using a micro-sensor array of miniaturised solid-state ion-selective electrodes to analyse sweat samples for sodium, potassium and chloride simultaneously is described. The array, incorporated into a miniature flow cell which is linked to a portable PC for data acquisition, constitutes a small, portable, and simple to use analytical instrument. Samples are passed through the flow cell and over the array and an immediate potentiometric response is obtained, which can be equated to the concentrations of sodium, chloride, potassium and other parameters in the sweat sample. Used here in conjunction with a Wescor Macroduct sweat sampling unit, it promises a much simplified, much less expensive procedure for sweat analysis than the procedures currently in common use.

Baboon/human homologies examined by spectral karyotyping (SKY): a visual comparison

Baboon (Papio hamadryas) metaphase chromosomes were analyzed using spectral karyotyping (SKY), a technique combining fluorescence microscopy, CCD-imaging, and Fourier spectroscopy. Results from a comparison of SKY analyses using probes derived from human chromosomes on baboon metaphases were consistent with the majority of comparative gene mapping data between the two species. These data were also compatible with earlier studies comparing macaque and human chromosomes. Human (HSA) chromosome 2 was homologous to baboon (PHA) chromosomes 12 (HSA 2q) and 13 (HSA 2p), whereas three baboon chromosomes corresponded to two different human chromosomes: PHA 3 to HSA 7 and HSA 21, PHA 7 to HSA 14 and HSA 15, and PHA 10 to HSA 20 and HSA 22. These results support the retained synteny between the Hominidae and Cercopithecidae genomes.

Swelling and delamination of multi-electrode sensor arrays studied by variable-pressure scanning electron microscopy

Multi-electrode sensor arrays are made of soft and wet materials not easily examined by most microscopic techniques. In this paper, we have demonstrated that low-vacuum scanning electron microscopy (LVSEM) and energy-dispersive X-ray analysis (EDX) are adequate for studying the hydration, swelling, and possible delamination of multi-electrode sensor arrays. We found that the LVSEM environment had no detectable effect on the morphology of Na(+), K(+), and Ca(++) sensors, and EDX analysis indicated that all three membranes have similar compositions. However, once hydrated, the sensors exhibited different behaviors. The K(+) and Ca(++) sensors swelled more than the Na(+) sensor did. This swelling is due principally to water sorption in the membrane. We believe that the larger thickness of the K(+) and Ca(++) membrane is partly responsible for the observed swelling effect. A simple Griffith analysis of the interface rupture confirms the experimental evidence that these thicker membranes also are more prone to delamination failure.

Development and application of surface plasmon resonance-based biosensors for the detection of cell-ligand interactions

Surface plasmon resonance (SPR)-based biosensors were investigated with a view to providing a portable, inexpensive alternative to existing technologies for "real-time" biomolecular interaction analysis of whole cell-ligand interactions. A fiber optic SPR-based (FOSPR) biosensor, employing wavelength-dependent SPR, was constructed to enable continuous real-time data acquisition. In addition, a commercially available integrated angle-dependent SPR-based refractometer (ISPR) was modified to facilitate biosensing applications. Solid-phase detection of whole red blood cells (RBCs) using affinity-captured blood group specific antibodies was demonstrated using the BIACORE 1000, BIACORE Probe, FOSPR, and ISPR sensors. Nonspecific binding of RBCs to the hydrogel-based biointerface was negligible. However, the background noise level of the FOSPR-based biosensor was approximately 25-fold higher than that of the widely used BIACORE 1000 system while that of the ISPR-based biosensor was over 100-fold higher. Nevertheless, the FOSPR biosensor was suitable for the analysis of macromolecular analytes contained in crude matrices.

Sibling vesicoureteral reflux in multiple gestation births

BACKGROUND

Vesicoureteral reflux (VUR) is the most commonly inherited disease of the genitourinary tract. Although the majority of evidence supports a genetic cause, the tendency for this condition to spontaneously improve over time has made it difficult to determine the actual mode of transmission. We report the incidence of VUR in siblings of multiple gestation births and for the first time compare the relative incidence of reflux between identical and fraternal twins.

METHODS

A database consisting of all radionuclide cystograms and voiding cystourethrograms performed between the years 1986 and 1996 was searched for multiple gestation births. The medical records of each patient were evaluated for age at presentation, zygosity, reflux grade, and time to resolution. Children with secondary causes of VUR (eg, posterior urethral valves) were excluded. Triplets were treated as 2 pairs of twins for statistical analysis.

RESULTS

Forty-six pairs met the inclusion criteria (31 dizygotic and 15 monozygotic). Overall, 23 (50%) of 46 siblings of index cases had demonstrable VUR. Comparison of VUR prevalence between identical and nonidentical twins was revealing with 80% (12/15) of identical twins and 35% (11/31) of fraternal twins having VUR. When only the youngest individuals in each group were considered, 100% (7/7) of the monozygotics and 50% (5/10) of the dizygotics demonstrated this trait.

CONCLUSIONS

High concordance for VUR in identical twin siblings supports a genetic basis for the transmission of this disease. Results obtained from fraternal twin siblings provides convincing evidence that this trait is transmitted in an autosomal dominant fashion.

The incidence of intersexuality in children with cryptorchidism and hypospadias: stratification based on gonadal palpability and meatal position

PURPOSE

The combined findings of cryptorchidism and hypospadias often indicate the existence of an intersex state. Testicular maldescent and incomplete tubularization of the urethral plate occur in a spectrum with the severity of the 2 processes likely dependent on the degree of pathophysiology in the androgenic hormonal axis. The incidence of intersexuality in children with undescended testes, hypospadias and otherwise nonambiguous male genitalia has been reported to be 27%. Although the likelihood of genotypic or gonadal ambiguity has previously been associated with meatal position in this population, to our knowledge our study is the first to evaluate the incidence of intersexuality relative to whether the undescended testis is palpable or nonpalpable.

MATERIALS AND METHODS

The database at our hospital was searched for all cases of undescended testes (2,105) and hypospadias (1,057) between 1982 and 1996. Radiographic, histological and karyotypic data were compiled for all patients presenting with both diagnoses. Gonadal palpability (palpable versus nonpalpable) and meatal position (anterior versus mid versus posterior) were recorded and correlated with the likelihood of identifying an intersex condition. Ten boys with a diagnosis of undescended testes subsequent to inguinal hernial repair were excluded from study. Patients with congenital adrenal hyperplasia or complete testicular feminization were also excluded from study due to the clearly female appearance of the external genitalia. Statistical significance was assessed using Fisher's exact test.

RESULTS

We identified 79 patients presenting with undescended testes, hypospadias and a phallus that was believed to be a possible penis. Intersex conditions were identified with nearly equal frequency in the 44 cases of unilateral (30%) and 35 of bilateral (32%) cryptorchidism. In the unilateral undescended testes group patients with a nonpalpable testis were at least 3-fold more likely to have an intersex condition than those with a palpable undescended testis (50 versus 15%, p = 0.02). In the bilateral group patients with 1 or more nonpalpable testes were also nearly 3-fold as likely to have an intersex condition than those with bilateral palpable undescended gonads (47 versus 16%, p = 0.07). Meatal position was graded as anterior in 33% of cases, mid in 25% and posterior in 41% with the more posterior location conferring a significantly greater likelihood of an intersex condition (anterior 2 of 26, mid 1 of 20 and posterior 21 of 33).

CONCLUSIONS

Gonadal palpability is an important predictor of an intersex state in unilateral and bilateral cases of cryptorchidism with hypospadias. Patients with an undescended testis that cannot be palpated are significantly more likely to have an intersex condition than those in whom the undescended testis may be palpated on physical examination. The severity of hypospadias likewise has a strong positive correlation with an intersex state.

Type-II external fixation, using new clamps and positive-profile threaded pins, for treatment of fractures of the radius and tibia in dogs

A new external fixation system for repair of fractures of the radius and tibia was developed that uses positive-profile threaded pins. This system allows for addition of a fixation clamp between 2 installed clamps, predrilling of pin holes through a drill sleeve, use of positive-profile threaded pins in all locations, and easier application of full pins. Type-II external fixators were applied, using this system, to fractures in 10 client-owned dogs, and outcome was evaluated. All fractures healed without complications. Duration of surgery, mean time until radiographic evidence of a bridging callus, and mean time until removal of the external fixator were shorter, and frequency of pin loosening were less than with other techniques. Pin loosening was uncommon. This system provides an important improvement in external skeletal fixation.

Voltammetric detection for capillary electrophoresis

Several approaches to implementing amperometric detection for capillary electrophoresis have been reported. This report describes the development of a voltammetric detector for CE. The detector is designed to minimize distortion of the voltammetry due to ohmic potential drop. This was accomplished by using a cast Nafion detection cell at the end of the separation capillary. The cast Nafion detection cell provided a low-dead-volume, low-resistance cell that minimized ohmic potential drop and peak band broadening. The ability to detect the current due to oxidation of analytes superimposed on a large background current was also improved. A dynamic background subtraction scheme was used in which a second working electrode, positioned in the electrochemical cell but outside of the detection cell, was used to compensate for the background current in real time. The output of the compensating working electrode was subtracted from the output of the detecting working electrode prior to analog-to-digital conversion. Postexperimental digital background subtraction was also implemented. This approach provided optimal elimination of the background current with maximal detection of the analytical signal. The voltammetric detector developed produced high-quality voltammetric response of analytes with injected concentrations as low as 0.20 microM. The system was evaluated by obtaining CE voltammograms of a mixture of eight test phenolic acids.

Novel instrumentation for real-time monitoring using miniaturized flow systems with integrated biosensors

A prototype miniaturized Total Chemical Analysis System (muTAS) has been developed and applied to on-line monitoring of glucose and lactate in the core blood of anaesthetized dogs. The system consists of a highly efficient microdialysis sampling interface sited in a small-scale extracorporeal shunt circuit ('MiniShunt'), a silicon machined microflow manifold and integrated biosensor array for glucose and lactate detection with associated computer software for analytical process control. During in-vivo testing the device allowed real-time on-screen monitoring of glucose and lactate with system response times of less than 5 min, made possible by the small dead volume of the microflow system. On-line glucose and lactate measurements were made in the basal state as well as during intravenous infusion of glucose or lactate. The prototype muTAS is currently suitable for trend monitoring but refinements are necessary before application of the system for determination of individual lactate values.

In vitro optimisation of a microdialysis system with potential for on-line monitoring of lactate and glucose in biological samples

The optimisation and evaluation of the microdialysis component of a prototype miniaturised total analysis system for application in the continuous monitoring of lactate and glucose is reported. The complete unit comprises a high efficiency microdialysis sampling system, a miniaturised microflow manifold with an integrated biosensor array, together with the hardware and software necessary for controlling the flow parameters and monitoring the sensor signals. Sampling occurs via a microdialysis shunt probe which is perfused continuously with a physiological buffered saline solution. The continuous dialysate outflow is presented to the biosensor array, resulting in the appropriate amperometric signals. Aspects of technological significance addressed here include probe membrane size, perfusate flow rate, sample flow rate, temperature change, probe sterilisation procedures, and heparin content of the physiological saline solution employed.

Defining the limits of survivorship after very severe head injury

BACKGROUND

Reliable prediction of outcome after head injury is a daunting task. Although previous reports have highlighted the difficulties of determining outcome in the cohort of severe head injury Glasgow Coma Scale (GCS) score < or = 8), we wondered within the very severely injured population (GCS score 3-5) if a simple combination of clinical parameters may be predictive of poor outcome.

METHODS

All patients admitted to a Level 1 trauma center with a GCS score of 3 to 5 from 1986 to 1991 inclusive (380 patients) were retrospectively reviewed and outcome a minimum of 6 months after injury was determined by chart review or telephone.

RESULTS

Follow-up was accomplished in all but five patients (1.3%). Functional survival (nonvegetative) was correlated to admission GCS score, pupillary abnormalities, and age. As anticipated, overall functional survival was poor (12.5%), and even worse among those evidencing pupillary abnormalities (6.6%). Interestingly, there was an absence of survivors in the advanced age decades, with the oldest functional survivor of any GCS increasing in a stepwise fashion with increasing coma score. This translated into the oldest survivor of a GCS score of 3 being in their chronologic 30s, a score of 4 in their 40s, and a score of 5 in their 50s. Among patients older than these age decades, that is beyond this simple age/GCS cut-off (32.8% of cohort), there were no functional survivors (95% confidence interval 0, 2.4).

CONCLUSIONS

Within the population of very severely head injured patients (GCS score 3-5), the simple combination of age and admission GCS score appears to predict accurately non-functional outcome in almost one third of patients. If confirmed at other centers, this may have wide-ranging implications regarding counseling of families, utilization of resources, and the design of head injury studies.

The effect of prior fear levels on UCS-expectancy ratings to a fear-relevant stimulus

This study investigated the effect of levels of prior fear to a fear-relevant stimulus on UCS expectancy ratings in a threat conditioning procedure. The results suggested that UCS-expectancy ratings are independently influenced by both the nature of the stimulus (whether it is fear-relevant or fear-irrelevant) and the level of prior fear to the stimulus. Furthermore, significantly higher UCS-expectancy levels caused by prior fear and stimulus type were accompanied in some stages of the experiment by greater magnitudes of skin conductance responses during the stimulus.

The use of differential measurements with a glucose biosensor for interference compensation during glucose determinations by flow injection analysis

A novel detection system for the determination of glucose in the presence of clinically important interferents, based on the use of dual sensors and flow-injection analysis (FIA), is described. The normalisation methodology involves measurement of the interference signal at a reference sensor; this signal can then be subtracted from the glucose sensor signal (post-run) to give a corrected measurement of the glucose concentration. The detection system consists of a thin layer with dual glassy carbon working electrodes. One electrode was surface modified to act as a glucose biosensor by immobilisation of glucose oxidase (GOx) (from Aspergillus niger) with 1% glutaraldehyde and bovine serum albumin. The second electrode (glucose oxidase omitted) was utilised to measure the interference signal responding only to electroactive species present in the injected sample. A computer controlled multichannel potentiostat was used for potential application and current monitoring duties. The sensor responses were saved in ASCII format to facilitate post-run analysis in Microsoft Excel. Cyclic voltammetry (CV) was utilised to investigate the manner in which the interference signal contributed to the total signal obtained at the biosensor in the presence of glucose. The kinetics parameters Imax and the apparent Michaelis-Menten constant, K'm, were calculated for the sensor operating under flow-injection conditions.

Disturbed attachment and negative affective style. An intergenerational spiral

The relationship between the quality of parents' attachment to their own parents and the quality of affective style was examined with a sample of 49 severely disturbed young adults and adolescents and their families receiving long-term in-patient treatment. Measures reflecting disturbances in attachment of parents to their own parents, derived from a five-minute speech sample task, were strongly associated with measures of negative affective style (e.g., criticism, intrusiveness and guilt induction) in face-to-face interactions with the disturbed offspring, as assessed through videotaped discussions of conflictual family issues after three months of treatment. The most significant findings involved the linkages between disturbances in the mother's attachment to her own mother and the degree of negative affect directed at the child patient. The association between disturbed intergenerational parental attachments and negative affective style supports the hypothesis that the parent's own internal burdens, stemming from disturbed attachment representations, particularly of the same-sex parent, may be a driving force behind the negative affect they display in interactions with their disturbed offspring.

Dependence of measured ionized calcium on protein concentration as measured by three ion-selective electrodes

A positive effect of protein on the measurement of ionized calcium in serum by ion-selective electrodes (ISEs) has been previously reported and the present study confirms this finding. Ionized calcium in serum was measured in the presence of increasing protein concentrations induced by venous stasis in 17 healthy volunteer subjects. Ionized calcium was measured using two commercial analysers, a Radiometer ICA2 analyser and a Baker Analyte+2 analyser, and a calcium cell devised by Covington for the calcium reference method (CRM). Both commercial analysers used charged ionophores and the CRM used a neutral carrier ionophore in the selective membrane. A small but significant rise in ionized calcium with increasing protein was measured on all analysers. Substitution of isotonic KCl for saturated KCl in the reference electrode of the CRM resulted in significantly reduced values for ionized calcium in paired serum samples when measured using the isotonic salt bridge. This study supports the premise that the positive effect of protein is related to the salt bridge concentration of the reference electrode rather than the ISE membrane composition.

Ultrasound-guided hepatic cryosurgery in the treatment of metastatic colon carcinoma. Preliminary results

Cryosurgery, the in situ freezing of cancer, has been proposed in the past as a possible treatment for unresectable hepatic tumors. Its advantage lies in the fact that it is a very focal treatment sacrificing less normal tissue than surgical resection, allowing treatment of multiple lobes. Because cryosurgery does not affect large vessels, tumors in difficult locations, such as adjacent to the inferior vena cava (IVC), can be treated. With the use of intraoperative ultrasound to place the cryoprobes and monitor the freezing process, 18 patients with unresectable metastatic colon carcinoma confined to the liver were treated. Of the 18 patients treated, 4 (22%) are in complete remission as determined by computed tomography (CT) scans and carcinoembryonic antigen (CEA) levels, with a mean follow-up of 28.8 months. Four patients (22%) were not adequately treated at the time of cryosurgery. The number of lesions frozen in each patient ranged from 1 to 12, with a mean of 6 lesions. Fourteen patients had bilobar disease; three patients had previous right lobectomies with recurrences in their remaining left lobes prior to cryosurgery, and one patient had unilobar disease. Mean survival of the 14 cases with recurrence was 21.4 months, with 2 of the 14 still alive. Ultrasound-guided hepatic cryosurgery appears to be an effective treatment for metastatic colon carcinoma to the liver that is unresectable (including patients with bilobar and multiple lesions). These preliminary results indicate that the procedure warrants further study.

Adsorptive stripping voltammetric determination of pipemidic acid in human urine

The electrochemical behaviour of pipemidic acid (8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)-pyrido[2,3-d]pyrimidine-6- carboxylic acid), a well known antimicrobial agent used for urinary infections, was investigated by linear-sweep, differential-pulse and square-wave voltammetry at a hanging mercury drop electrode. Two reduction processes were observed in Britton-Robinson buffers at acid pH, whereas only one or two processes were observed in alkaline solutions, dependent on the pH of the buffer employed. Adsorptive effects were used to accumulate the drug on to the electrode. The adsorbed species were measured voltammetrically by using a cathodic process appearing at -0.76 V in 0.1 M HCIO4. Linear calibration graphs were obtained in the range 2.5 x 10(-9)-2.0 x 10(-7) M. A simple procedure of extraction was employed for the determination of the drug in urine samples.

Cirrhosis in the trauma victim. Effect on mortality rates

To evaluate the impact cirrhosis has on survival the records of 40 cirrhotic trauma victims from the registries of two Level 1 trauma centers were reviewed and probability of survival calculated using the TRISS methodology. Mechanism of injury, anatomic location, involvement of single or multiple sites, presence of ascites, elevations in serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase, serum bilirubin, prothrombin time (PT), and hypoalbuminemia were tabulated for each patient. Contingency tables were created for injury and hepatic parameters, as related to survival, and subjected to chi square analysis. Loglinear analysis was performed on all significant parameters to evaluate the independent effects of injury characteristics and hepatic insufficiency on survival. Predicted survival was 93%; observed survival was 70% (Z = -6.92; p less than 0.001). Cause of death was multiple-system organ failure (9) and closed head injury (3). Admission markers of poor outcome included one or more of the following: ascites, elevated PT or bilirubin, history of motor vehicle accident, multiple trauma, or blunt abdominal trauma requiring laparotomy. Loglinear analysis revealed that the presence of ascites, elevated PT, or bilirubin, further diminished the rate of survival for any individual injury characteristic. We concluded that survival among cirrhotic trauma victims was significantly lower than predicted. In addition the presence of hepatic insufficiency further diminishes survival, regardless of the injury sustained.

Comparison of a calixarene-based ion-selective electrode with two automated analyzers for the clinical determination of sodium in blood plasma

Neutral-carrier ion-selective electrodes based on methyl p-t-butylcalix[4]aryl acetate have been prepared that are responsive to sodium ions. The miniaturized catheter-type electrodes were obtained by dip-coating their porcelain tips in a PVC membrane cocktail. Examination of the general performance of the electrodes revealed excellent characteristics in terms of Nernstian response, selectivity, stability, reproducibility and response time. The results from the indirect potentiometric assessment of a large number of plasma samples with the electrodes showed a good correlation with the results from two automated analyzers (Technicon Smac 3, Hitachi 704) and with flame photometric data. Although inconsistencies were observed in the measurement of some plasma samples, the variance seemed to be method-dependent, and the overall performance of the electrodes showed promise as an alternative to the sodium glass electrode. Some factors influencing the standard potential of the measuring cell are discussed as a source of error.

The effect of streptozotocin-induced diabetes on the neuroendocrine-male reproductive tract axis of the adult rat

Studies in the streptozotocin rat model for diabetes mellitus suggest that sexual dysfunction in these animals may result from diabetes-induced alterations of the neuroendocrine-reproductive tract axis. Our investigation was performed to better define the effects of diabetes on the neuroendocrine sex accessory organ axis in the male rat. Rats were rendered diabetic, and were either left untreated or treated with insulin, testosterone or both. Diabetes resulted in decreased body and reproductive organ weights, as well as diminished sperm counts and motility and prostatic acid phosphatase. Seminal fructose was increased. A significant decrease in serum LH, FSH and testosterone was noted. Insulin treatment of the diabetic rats restored serum gonadotropins, reproductive organ weight, sperm counts and motility, and seminal fructose to control levels. Prostatic weight and prostatic acid phosphatase levels remained abnormal. Testosterone restored the above mentioned parameters to control levels, with the exception of LH. Treatment with insulin and testosterone had a synergistic effect on spermatogenesis. A GnRH stimulation test demonstrated that pituitaries of diabetic animals had a blunted response, with diminished LH and FSH secretion. In the diabetic animal, there are both pituitary and testicular abnormalities which may be responsible for reproductive dysfunction.

Dentate granule cells in the rat hippocampal formation have the behavioral characteristics of theta neurons

Recordings were made from the dentate gyrus granule cell layer of freely-moving rats. The neurons recorded from the layer were divisible into 3 classes using a combination of electrophysiological and behavioral criteria; the duration of the extracellularly recorded unfiltered action potential provided the most reliable means of differentiating between cell types. Class I and class II neurons always fired in short duration single action potentials, while class III neurons had broader waveforms and occasionally were observed to fire complex spikes. As the most obvious behavioral correlate of class I and class II neurons was movement of the rat, these cells correspond to the theta cells of Ranck. Class III neurons for which a behavioral correlate was observed had the characteristics of the place cells described by O'Keefe. The neurons of classes I and II comprised 89% (56 of 63) of the total population sampled in the granule cell layer. Most of these neurons (49 of 56) discharged at short latency in response to a stimulus delivered via the perforant pathway; in contrast, none of the class III neurons observed were activated in this way. Horseradish peroxidase or Fast Green dye ejection through glass microelectrodes recording class I cell activity in urethane-anesthetized animals revealed the electrode tip to be in the granule cell layer in 27 of 27 cases. Six single class I neurons were also antidromically activated by a stimulus from an electrode placed in the hippocampal mossy fibers, and collision testing was successful in all cases. It is concluded that the dentate granule cells are theta cells.

Disproportionate expression of the two nonallelic rat insulin genes in a pancreatic tumor is due to translational control

The expression of the two nonallelic but highly homologous rat insulin genes (1 and 2) in a transplantable beta-cell tumor is found to be 10-fold higher for rat1 insulin than rat2 insulin, while in normal pancreatic tissue there are approximately equal amounts of each protein. No large sequence rearrangements of the genes were apparent by restriction analysis of the tumor DNA, and both genes were found to be specifically hypomethylated in the tumor as compared with other nonpancreatic tissue. Equivalent amounts of both insulin 1 and 2 precursor transcripts, as well as stable, mature mRNAs were detected in the tumor. However, two-dimensional gel analysis of immunoprecipitated rat1 and rat2 preproinsulins synthesized in vitro revealed a 10:1 ratio of rat1 to rat2 proteins. A 1:1 ratio was obtained when the tumor mRNA was treated in vitro with vaccinia virus capping extract, suggesting a structural modification at the 5' terminus of the rat2 mRNA. These results are discussed in the context of insulin regulation by glucose, shown to be due to translational control.

Management of chronic peritoneal catheter malfunction

This paper presents a modification of Tenckhoff's insertion procedure for chronic peritoneal dialysis catheters and reviews the results of a technique of management of catheter malfunction by manipulation which obviates the need for catheter replacement. 43 catheters in 33 patients were observed for no less than 1 year. Catheters which malfunctioned within 3 weeks benefited only marginally from manipulation. In those catheters which functioned for more than 3 weeks, manipulation extended mean survival time by 103% (8.5-17.3 months) and overall survival did not differ statistically from catheters not requiring manipulation. The technique is safe and simple and contributes to the effective management of patients undergoing chronic peritoneal dialysis.

Torso mounted electrocardiographic electrodes for routine clinical electrocardiography

An easily applicable lead system similar to that proposed by Mason and Likar in 1966 for stress electrocardiography provides quantitative and qualitative electrocardiographic information and diagnoses similar to those derived from the "standard" lead system using only torso placement of ten electrodes.