Predicting no-show appointments in a pediatric hospital in Chile using machine learning.

The Chilean public health system serves 74% of the country's population, and 19% of medical appointments are missed on average because of no-shows. The national goal is 15%, which coincides with the average no-show rate reported in the private healthcare system. Our case study, Doctor Luis Calvo Mackenna Hospital, is a public high-complexity pediatric hospital and teaching center in Santiago, Chile. Historically, it has had high no-show rates, up to 29% in certain medical specialties. Using machine learning algorithms to predict no-shows of pediatric patients in terms of demographic, social, and historical variables. To propose and evaluate metrics to assess these models, accounting for the cost-effective impact of possible intervention strategies to reduce no-shows. We analyze the relationship between a no-show and demographic, social, and historical variables, between 2015 and 2018, through the following traditional machine learning algorithms: Random Forest, Logistic Regression, Support Vector Machines, AdaBoost and algorithms to alleviate the problem of class imbalance, such as RUS Boost, Balanced Random Forest, Balanced Bagging and Easy Ensemble. These class imbalances arise from the relatively low number of no-shows to the total number of appointments. Instead of the default thresholds used by each method, we computed alternative ones via the minimization of a weighted average of type I and II errors based on cost-effectiveness criteria. 20.4% of the 395,963 appointments considered presented no-shows, with ophthalmology showing the highest rate among specialties at 29.1%. Patients in the most deprived socioeconomic group according to their insurance type and commune of residence and those in their second infancy had the highest no-show rate. The history of non-attendance is strongly related to future no-shows. An 8-week experimental design measured a decrease in no-shows of 10.3 percentage points when using our reminder strategy compared to a control group. Among the variables analyzed, those related to patients' historical behavior, the reservation delay from the creation of the appointment, and variables that can be associated with the most disadvantaged socioeconomic group, are the most relevant to predict a no-show. Moreover, the introduction of new cost-effective metrics significantly impacts the validity of our prediction models. Using a prototype to call patients with the highest risk of no-shows resulted in a noticeable decrease in the overall no-show rate.

Fracture incidence after 3 years of aromatase inhibitor therapy.

BACKGROUND: The purpose of this study was to describe the fracture incidence and bone mineral density (BMD) evolution in a large cohort of post-menopausal women with breast cancer after 3 years of aromatase inhibitor (AI) therapy. PATIENTS AND METHODS: A prospective, longitudinal study in real-life setting. Each woman had an extensive medical assessment, a biological evaluation, a BMD measurement, and systematic spinal X-rays at baseline and after 3 years of AI therapy. Women with osteoporosis at baseline (T-score < -2.5 and/or non-traumatic fracture history) were treated by oral weekly bisphosphonates. RESULTS: Among 497 women (mean age 63.8 ± 9.6 years) included in this study, 389 had a bone evaluation both at baseline and after 3 years of AI therapy: 267 women (mean age 61.2 ± 8.6) with no osteoporosis at baseline and 122 women (mean age 67.2 ± 9.1) with osteoporosis at baseline justifying a weekly oral bisphosphonate treatment. Women without bisphosphonates had a significant decrease in spine BMD (-3.5%, P < 0.01), neck BMD (-2.0%, P < 0.01), and total hip BMD (-2.1%, P < 0.01) over the 3 years but only 15 of them (5.6%) presented an incident vertebral or non-vertebral fracture. In osteoporotic women treated with bisphosphonates, spine and hip BMD were maintained at 3 years but 12 of them (9.8%) had an incident fracture. These fractured women were significantly older (74.1 ± 9.8 versus 66.5 ± 8.8) but also presented BMD loss during treatment suggesting poor adherence to bisphosphonate treatment. CONCLUSION: This real-life study confirmed that AIs induced moderate bone loss and low fracture incidence in post-menopausal women without initial osteoporosis. In women with baseline osteoporosis and AI therapy, oral bisphosphonates maintain BMD but were associated with a persistent fracture risk, particularly in older women.

Adaptive thermogenesis can make a difference in the ability of obese individuals to lose body weight.

The decrease in energy expenditure that occurs during weight loss is a process that attenuates over time the impact of a restrictive diet on energy balance up to a point beyond which no further weight loss seems to be possible. For some health professionals, such a diminished energy expenditure is the normal consequence of a progressive decrease in the motivation to exercise over the course of a weight-reducing program. Another explanation of decreased energy needs during weight loss is the decrease in body energy stores (that is, fat mass and muscle mass) and its related obligatory costs of living. Many studies have also documented the existence of adaptive thermogenesis in the context of weight loss, which represents a greater-than-predicted decrease in energy expenditure. In this paper, we pursue the analysis of this phenomenon by demonstrating that an adaptive decrease in thermogenesis can have a major role in the occurrence of resistance to further lose fat in weight-reduced obese individuals. Evidence is also presented to support the idea of greater hunger sensations in individuals displaying more pronounced thermogenic changes. Finally, as the decrease in thermogenesis persists over time, it is also likely associated with a greater predisposition to body-weight regain after weight loss. Globally, these observations suggest that the adaptive reduction in thermogenesis that accompanies a prolonged negative energy balance is a major determinant of the ability to spontaneously lose body fat.

First Report of Sugarcane Leaf Scald in Gabon Caused by a Highly Virulent and Aggressive Strain of Xanthomonas albilineans.

During a disease inspection at the sugarcane estate SUCAF near Franceville, Gabon, in March 2011, 0.5 to 1 cm wide chlorotic stripes covered with many small red streaks were observed on sugarcane (Saccharum spp.) leaves of a single plant of cultivar R581. After removal of the leaves covering the base of the stalks, abnormal development of basal side shoots was also observed. Transversal sections of a diseased stalk showed reddening of the vessels near the nodes. Circular, convex, smooth, shiny, translucent, non-mucoid, honey-yellow pigmented bacterial colonies were isolated from stalk pieces and side shoots on XAS selective agar medium (1). The nucleotide sequence of the 16S-23S internal transcribed spacer (ITS) of a representative colony was shown to be 100% identical to the 16S-23S ITS sequence from the genome of Xanthomonas albilineans strain GPE PC73 (GenBank: FP565176.1). This strain from Gabon was named GAB266. Sugarcane stalks of greenhouse grown cultivar CP68-1026 were inoculated with X. albilineans strains XaFL07-1 from Florida, GPE PC73 from Guadeloupe, and GAB266. Five stalks were inoculated by the modified decapitation method (3) with each strain or with a water control. One month post-inoculation (MPI), white pencil lines and severe necrosis were observed on leaves inoculated with strains XaFL07-1 and GPE PC73, and no disease symptoms appeared on non-inoculated leaves that developed 2 to 3 MPI. These results are in agreement with those generally obtained after inoculation of susceptible sugarcane cultivars with X. albilineans strains from various geographical locations under greenhouse conditions (Rott, unpublished results). In contrast, 1 MPI, only discrete white to red pencil lines were observed along with necrosis on leaves inoculated with strain GAB266, and by 2 to 3 MPI, all five inoculated plants were wilted. The pathogen was successfully reisolated by the stalk blot inoculation technique (3) with XAS medium, from all five inoculated stalks and from 98 of 114 internodes. In a second greenhouse experiment, the same three strains of X. albilineans were inoculated as described above into five sugarcane cultivars differing in resistance to leaf scald in Guadeloupe (2) (CP68-1026, highly susceptible; B69566, susceptible; R570, tolerant; B8008, resistant; Co6415, highly resistant). The same symptoms as those described above were again observed on inoculated leaves of the five sugarcane cultivars 1 MPI. Strains XaFL07-1 and GPE PC73 produced occasionally a single pencil line on non-inoculated leaves 2 to 3 MPI, but only strain GAB266 caused leaf scalding and/or plant death 2 to 3 MPI: cultivar CP68-1026 (5 of 5 plants), B69566 (5 of 5 plants), R570 (4 of 5 plants), B8008 (5 of 5 plants), and only non-inoculated leaves of cultivar Co6415 remained symptomless (5 plants). Strain GAB266 from Gabon appeared, therefore, more virulent and aggressive than the two strains of X. albilineans from Florida and Guadeloupe. To our knowledge, this is the first report of leaf scald of sugarcane in Gabon and the first description of an unusual highly virulent and aggressive strain of X. albilineans. A large-scale survey needs to be undertaken to determine the distribution of leaf scald disease and this new pathotype/race of X. albilineans in Gabon and other geographical locations. References: (1) M. J. Davis et al. Plant Dis. 78:78, 1994. (2) P. Rott et al. Phytopathology 87:1202, 1997 (3) P. Rott et al. Mol. Plant-Microbe Interact. 24:594, 2011.

Menopausal symptoms appear before the menopause and persist 5 years beyond: a detailed analysis of a multinational study.

OBJECTIVE: Few Latin American studies have described menopausal symptoms in detail by means of a standardized assessment tool. The objective of this study was to assess the prevalence and severity of menopausal symptoms and their impact over quality of life among mid-aged Latin American women. METHOD: In this cross-sectional study, 8373 otherwise healthy women aged 40-59 years from 12 Latin American countries were asked to fill out the Menopause Rating Scale (MRS) and a questionnaire containing personal sociodemographic data. Menopause status (pre-, peri- and postmenopausal) was defined according to the criteria of the Stages of Reproductive Aging Workshop. RESULTS: Of all the studied women, 90.9% had at least one menopausal symptom (complaint) that they rated. Muscle and joint discomfort, physical and mental exhaustion and depressive mood were highly prevalent and rated as severe-very severe (scores of 3 and 4), at a higher rate than vasomotor symptoms (15.6%, 13.8% and 13.7% vs. 9.6%, respectively). Of premenopausal women (40-44 years), 77.0% reported at least one rated complaint, with 12.9% displaying MRS scores defined as severe (> 16). The latter rate increased to 26.4% in perimenopausal, 31.6% in early postmenopausal and 29.9% among late postmenopausal women. As measured with the MRS, the presence of hot flushes increased the risk of impairment of overall quality of life in both premenopausal (odds ratio 12.67; 95% confidence interval 9.53-16.83) and peri/postmenopausal women (odds ratio 9.37; 95% confidence interval 7.85-11.19). CONCLUSION: In this large, mid-aged, female Latin American series, muscle/joint discomfort and psychological symptoms were the most prevalent and severely rated menopausal symptoms. The symptoms appear early in the premenopause, significantly impair quality of life and persist 5 years beyond the menopause.

A general swimming response in exhausted obligate swimming fish.

Marine organisms normally swim at elevated speeds relative to cruising speeds only during strenuous activity, such as predation or escape. We measured swimming speeds of 29 ram ventilating sharks from 10 species and of three Atlantic bluefin tunas immediately after exhaustive exercise (fighting a capture by hook-and-line) and unexpectedly found all individuals exhibited a uniform mechanical response, with swimming speed initially two times higher than the cruising speeds reached approximately 6 h later. We hypothesized that elevated swimming behaviour is a means to increase energetic demand and drive the removal of lactate accumulated during capture via oxidation. To explore this hypothesis, we estimated the mechanical work that must have been spent by an animal to elevate its swim speed and then showed that the amount of lactate that could have been oxidized to fuel it comprises a significant portion of the amount of lactate normally observed in fishes after exhaustive exercise. An estimate for the full energetic cost of the catch-and-release event ensued.

Efficacy and tolerability of methotrexate in severe childhood alopecia areata.

BACKGROUND: Alopecia areata (AA) occurring in childhood is associated with a poorer prognosis than adult AA and may severely affect quality of life. The efficacy of methotrexate (MTX) was reported in adults with AA but there is little information about its use in children. OBJECTIVES: We aimed to assess the efficacy and safety of MTX in severe childhood AA. METHODS: We conducted a retrospective study including children with severe AA treated with MTX in the Departments of Paediatric Dermatology in France between November 2005 and December 2009. RESULTS: Fourteen children (eight girls and six boys) aged between 8 and 18 years (mean 14·7) were included. AA was present for a mean duration of 5·7 years (range 2 months-11 years 8 months). The treatment was administered once weekly, the mean maximal dose was 18·9 mg weekly (range 15-25) and the mean duration of treatment was 14·2 months (range 1-31). Thirteen children were assessable. Of these 13 children, MTX was considered as successful (regrowth >50% of hair) for five of them. The remaining eight children were considered treatment failures. No serious side-effects were reported. CONCLUSIONS: The efficacy of MTX in children with severe AA is variable. MTX may be considered for severe childhood AA in the absence of alternative effective treatments.

Effect of endogenous estradiol levels on bone resorption and bone mineral density in healthy postmenopausal women: a prospective study.

OBJECTIVE: To investigate the effect of endogenous estrogens on bone mineral density (BMD) and bone markers in postmenopausal women over 24 months. METHODS: Fifty out of 99 postmenopausal women seen previously were re-assessed after 24 months. Levels of BMD, bone markers, serum estradiol (E(2)) and total testosterone were determined. RESULTS: BMD decreased in the femoral neck ( approximately 2%) (p < 0.008), but remained stable in the other skeletal areas; E(2) and serum Crosslaps (sCTX) decreased by 34% (p < 0.001) and 21% (p < 0.003), respectively. Women aged < or = 65 years exhibited decreased BMD only in the femoral neck (2%, p < 0.01), without changes in bone markers. Women aged > 65 years exhibited a decrease in sCTX levels and stable BMD values at all skeletal sites. E(2) levels decreased similarly in both groups ( approximately 35%). Women with baseline E(2) levels > or = 10 pg/ml showed stable BMD in spite of their E(2) levels decreasing by 42% (p < 0.001); sCTX decreased by 21% (p < 0.01). Women with baseline E(2) levels < 10 pg/ml showed a 2% decrease (p < 0.001) in femoral neck BMD and a 19% decrease (p < 0.002) in E(2) levels, without changes in bone markers. CONCLUSION: Although endogenous E(2) decreased to around 7 pg/ml in these menopausal women, this level would seem to be sufficient to maintain BMD in almost all skeletal areas, and to be more effective in older women.

[Orange skin and xanthomas associated with lycopenaemia in a setting of type III dyslipoproteinemia]. / Coloration orangée des téguments et des xanthomes au cours d'une lycopénémie associée à une dyslipoprotéinémie de type III.

BACKGROUND: Type III hyperlipoproteinaemia (HLP) is a rare form of dyslipidaemia characterized by skin lesions such as palmar crease xanthoma and tuberous xanthomas. To our knowledge, there have been no previous reports of yellow-orange discoloration of the skin and xanthomas associated with this disease. CASE REPORT: A 61-year-old woman consulted for palmar crease xanthoma and tuberous xanthomas of the elbows with odd yellow-orange discoloration. Laboratory investigations demonstrated type-III HLP and a high serum lycopene level. After 14 weeks of lipid-lowering treatment, the xanthomas and discoloration showed improvement. In addition, lipid levels and serum lycopene had returned to normal. DISCUSSION: All cases of lycopenaemia reported in the literature followed excessive ingestion of lycopene in foods. We describe the first case of lycopenaemia with orange discoloration of xanthomas following raised serum lycopene but not involving excessive dietary intake. Type-III HLP was doubtless instrumental in the physiopathogenesis of these orange lesions.

Androgens in relationship to cardiovascular risk factors in the menopausal transition.

OBJECTIVE: To establish the relationship between androgens and cardiovascular disease (CVD) risk factors in the menopausal transition. METHODS: A total of 124 women were divided into four groups: 29 premenopausal (PreM), 35 women in the menopausal transition still menstruating (MTM), 29 women in the menopausal transition with 3-6 months amenorrhea (MTA), and 31 postmenopausal women (PostM). Levels of triglycerides, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, glucose and insulin were assayed in all samples and waist circumference was measured. In a subgroup of 83 women (19 PreM, 21 MTM, 28 MTA and 15 PostM), levels of total testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS) and estradiol were determined. The free androgen index, Homeostasis Model Assessment (HOMA) index, Quantitative Insulin Sensitivity Check Index (QUICKI) and McAuley index, estradiol/total testosterone and triglyceride/HDL cholesterol ratios were calculated. RESULTS: Androstenedione was higher in MTA vs. PostM women (p < 0.05); DHEAS was higher in PreM women vs. the other three groups (p < 0.05). Sex hormone binding globulin (SHBG) in MTM women was higher than in MTA women (p < 0.05); the free androgen index was lower in MTM women than in MTA and PostM women. SHBG and the free androgen index showed negative and positive correlations, respectively with waist circumference, insulin resistance and lipids. In a multiple regression analysis, considering waist circumference, neither free androgen index nor SHBG showed significant differences between groups. The waist circumference correlated only with SHBG (p = 0.022) and correlations between SHBG and insulin resistance markers continued to be significant, but relationships between SHBG and lipoproteins and all correlations found with free androgen index were lost. CONCLUSIONS: An increment in the androgenic milieu that correlates with abdominal fat, insulin resistance and atherogenic lipoproteins becomes evident after the menopausal transition and suggests that evaluation of cardiovascular disease risk in these women should include androgens, considering that abdominal obesity is one of the main determinants of the relationship between androgenic parameters and cardiovascular risk factors.

Awareness of potential valvulopathy risk with pergolide and changes in clinical practice after label change: a survey among European neurologists.

In response to concern about the reported frequency of ergot-associated valvulopathy in patients with Parkinson's disease (PD), Eli Lilly and Company updated the Risk Minimization Program for pergolide, changing the Summary of Product Characteristics (SmPC) and distributing a Dear Doctor Letter (DDL) highlighting the new label changes. A survey was conducted subsequently to assess neurologists' awareness of the revised SmPC and their resulting changes in practice. A random sample of 20.3% of neurologists (n = 4056) from 12 eligible EU countries were invited to participate. Of the target population of 247 neurologists who treated patients with PD, used pergolide in 2005, and were willing to participate, 244 (99%) responded. Overall awareness of the DDL and the SmPC changes was 94.2%. Over half (58.3%) of neurologists indicated that they prescribe pergolide exclusively as second-line treatment, although some (21.9%) used pergolide exclusively as first-line treatment. In response to the DDL, most neurologists perform echocardiograms before treatment (67.5%) and during treatment (76.7%), and over half (55%) avoid prescribing doses >5 mg/day. Overall, use of a DDL to communicate an SmPC change was effective in increasing the awareness of pergolide-associated valvulopathy and in modifying neurologists' clinical practice to minimize this risk.

High Variation in Pathogenicity of Genetically Closely Related Strains of Xanthomonas albilineans, the Sugarcane Leaf Scald Pathogen, in Guadeloupe.

ABSTRACT Pathogenicity of 75 strains of Xanthomonas albilineans from Guadeloupe was assessed by inoculation of sugarcane cv. B69566, which is susceptible to leaf scald, and 19 of the strains were selected as representative of the variation in pathogenicity observed based on stalk colonization. In vitro production of albicidin varied among these 19 strains, but the restriction fragment length polymorphism pattern of their albicidin biosynthesis genes was identical. Similarly, no genomic variation was found among strains by pulsed-field gel electrophoresis. Some variation among strains was found by amplified fragment length polymorphism, but no relationship between this genetic variation and variation in pathogenicity was found. Only 3 (pilB, rpfA, and xpsE) of 40 genes involved in pathogenicity of bacterial species closely related to X. albilineans could be amplified by polymerase chain reaction from total genomic DNA of all nine strains tested of X. albilineans differing in pathogenicity in Guadeloupe. Nucleotide sequences of these genes were 100% identical among strains, and a phylogenetic study with these genes and housekeeping genes efp and ihfA suggested that X. albilineans is on an evolutionary road between the X. campestris group and Xylella fastidiosa, another vascular plant pathogen. Sequencing of the complete genome of Xanthomonas albilineans could be the next step in deciphering molecular mechanisms involved in pathogenicity of X. albilineans.

Variation in Albicidin Biosynthesis Genes and in Pathogenicity of Xanthomonas albilineans, the Sugarcane Leaf Scald Pathogen.

ABSTRACT Total genomic DNA from 137 strains of Xanthomonas albilineans from worldwide locations was hybridized with two DNA probes that together harbor the entire 49-kb albicidin biosynthesis gene cluster and two additional 3-kb genomic regions required for albicidin production. Fourteen haplotypes and two major genetic groups (albicidin [ALB]-restriction fragment length polymorphism [RFLP] A and ALB-RFLP B) were identified, and strains that were isolated after recent outbreaks of leaf scald disease belonged to group ALB-RFLP B. Albicidin genetic diversity was very similar to the previously described genetic diversity of the pathogen based on the whole genome. No relationship was found between variability of albicidin biosynthesis genes and the amount of albicidin produced in vitro by X. albilineans. Leaf scald-susceptible sugarcane cv. H70-144 was inoculated with 20 strains of the pathogen belonging to different ALB-RFLP haplotypes. Among them, 10 strains from Guadeloupe belonged to the same ALB-RFLP group but differed in the amount of albicidin produced in vitro. Strains were distributed in at least three different pathogenicity groups based on symptom severity and pathogen population density in the stalk. These two pathogenicity factors varied concurrently; however, no relationship between variation in albicidin biosynthesis genes, variation in the amount of albicidin produced in vitro, and variation in pathogenicity of X. albilineans was found. Further investigation is necessary to identify other genes involved in pathogenicity of X. albilineans.

Factors associated with an increased risk of vertebral fracture in monoclonal gammopathies of undetermined significance.

Monoclonal gammopathies of undetermined significance (MGUS) have been shown to be associated with an increased risk of fractures. This study describes prospectively the bone status of MGUS patients and determines the factors associated with vertebral fracture. We included prospectively 201 patients with MGUS, incidentally discovered, and with no known history of osteoporosis: mean age 66.6±12.5 years, 48.3% women, 51.7% immunoglobulin G (IgG), 33.3% IgM and 10.4% IgA. Light chain was kappa in 64.2% patients. All patients had spinal radiographs and bone mineral density measurement in addition to gammopathy assessment. At least one prevalent non-traumatic vertebral fracture was discovered in 18.4% patients and equally distributed between men and women. Fractured patients were older, had a lower bone density and had also more frequently a lambda light chain isotype. Compared with patients with κ light chain, the odds ratio of being fractured for patients with λ light chain was 4.32 (95% confidence interval 1.80-11.16; P=0.002). These results suggest a high prevalence of non-traumatic vertebral fractures in MGUS associated with lambda light chain isotype and not only explained by low bone density.

MoMuLV-derived self-inactivating retroviral vectors possessing multiple cloning sites and expressing the resistance to either G418 or hygromycin B.

To facilitate cloning procedures in recombinant murine leukemia virus-derived retroviruses, we have constructed vectors that both carry a polylinker with multiple restriction sites and express resistance to either G418 or hygromycin B. Our vectors are self-inactivating retroviruses that suppress interferences between LTR enhancers and internal promoters and avoid transcriptional stimulation of host cell genes. They can also be used as expression vectors in direct transfection assays, since no translation initiation codon lies between the 5' LTR and the cloning polylinker.

Stability studies on horse antithymocyte globulin.

Two equine antithymocyte globulin preparations were studied with respect to their relative rosette inhibition activity after storage at 4 and 25 C. After storage at 4 C for 48 months no activity loss was observed; 25 C storage resulted in fragmentation and eventual loss of relative rosette inhibition activity. A third preparation was studied by monkey skin graft prolongation. During a 1-year period, there was no loss of immunosuppressive activity as measured by this method and the rosette inhibition assay.

Pharmacokinetic and tolerance studies of cefpodoxime after single- and multiple-dose oral administration of cefpodoxime proxetil.

Cefpodoxime proxetil, a third generation, broad-spectrum, oral cephalosporin, was administered in single doses of 100, 200, 400, 600, and 800 mg (dose expressed as cefpodoxime equivalents) and multiple doses of 100, 200, and 400 mg twice daily to healthy volunteers. The pharmacokinetics of the active metabolite, cefpodoxime, and tolerance of cefpodoxime proxetil were determined. Results from the single-dose study indicate that cefpodoxime exhibits nonlinear pharmacokinetics over the dose range of 100 to 800 mg. This nonlinearity is primarily due to differences in dose-normalized AUC and Cmax, urinary recovery, and half-life between one or more of the higher-dose treatment groups and the 100-mg dosing group. After multiple-dose (twice daily) administration for 15 days, steady state is achieved on the second day of dosing, and there is no drug accumulation. Cefpodoxime pharmacokinetics are linear with dose over the clinically relevant dosing range of 100 to 400 mg. Microbiologic and HPLC plasma assay results are highly correlated, with close agreement between HPLC- and microbiologic-determined pharmacokinetic parameter estimates. Cefpodoxime proxetil was well tolerated in both studies. The most frequent medical events were related to gastrointestinal problems and consisted of transient loose stools in three subjects in the single-dose study and antibiotic-associated diarrhea in one subject in the multiple-dose study.

Cholinergic inositol phosphate formation in striatal neurons is mediated by distinct mechanisms.

In murine striatal neurons devoid of functional synapses (6 days in vitro) the cholinergic agonists carbachol and arecoline evoked dose-dependent inositol phosphate (InsP) responses with mean log EC50s of -4.1 +/- 0.5 and -4.48 +/- 0.1, respectively. Carbachol (1 mM) and arecoline (1 mM) responses were insensitive to tetrodotoxin, a voltage-sensitive Na+ channel blocker, and were blocked by pirenzepine with relatively low affinity (logIC50 = -5.9 +/- 0.3 for the carbachol response and logIC50 = -5.8 +/- 0.3 for the arecoline response). After synaptogenesis (13 days in vitro) the maximal carbachol effect doubled whereas the arecoline response remained unchanged. This additional effect was sensitive to tetrodotoxin and the voltage-dependent Ca2+ channel blocker, omega-conotoxin. The tetrodotoxin-sensitive carbachol response was blocked by lower concentrations of pirenzepine than the tetrodotoxin-insensitive carbachol response. More than 75% of the InsP response evoked by low concentrations of muscarine (1 and 10 microM) was sensitive to tetrodotoxin whereas only 38% of the InsP response stimulated by 1 mM of muscarine could be blocked by tetrodotoxin. These results suggest that there are at least two different mechanisms (depending on the stage of development), activated most probably by two different muscarinic receptors responsible for the carbachol-induced InsP formation in striatal neurons.

Radioimmunoassay for medroxyprogesterone acetate (Provera) using the 11alpha-hydroxy succinyl conjugate.

PIP: The development of a radioimmunoassay for medroxyprogesterone acetate (MPA) employing rabbit antibodies made against a bovine serum albumin (BSA) conjugate of the hemisuccinate ester of 11alpha-hydroxy MPA are described. The 11alpa-hydroxyl group was introduced into MPA by a series of chemical and microbiological transformations. The acid succinate MPA was coupled to BSA by reacting it with N,N'-carbonyldiimidazole. Cross-reactivities of several MPA analogs were compared suing rabbit antisera developed against the C-11 conjugate of MPA and goat antiserum developed against a C-3 conjugate of MPA. Antibodies formed against the C-11 conjugate showed increased specificity to steroid analogs which changes in the C-21 side chain. The profiles of serum MPA levels vs time, measured with both the C-3 and C-11 antisera, after oral drug administration to the monkey were similar. After intramuscular drug administration to dogs, serum MPA levels measured with the C-3 antisera were consistently greater as compared with those with C-11 antisera. Factors affecting precipitation of the antibody-antigen complex, assay precision, and assay sensitivity were evaluated.^ieng