A diet-dependent host metabolite shapes the gut microbiota to protect from autoimmunity

Diet can protect from autoimmune disease; however, whether diet acts via the host and/or microbiome remains unclear. Here, we use a ketogenic diet (KD) as a model to dissect these complex interactions. A KD rescued the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis in a microbiota-dependent fashion. Dietary supplementation with a single KD-dependent host metabolite (β-hydroxybutyrate, βHB) rescued EAE whereas transgenic mice unable to produce βHB in the intestine developed more severe disease. Transplantation of the βHB-shaped gut microbiota was protective. Lactobacillus sequence variants were associated with decreased T helper 17 (Th17) cell activation in vitro . Finally, we isolated a L. murinus strain that protected from EAE, which was phenocopied by the Lactobacillus metabolite indole lactic acid. Thus, diet alters the immunomodulatory potential of the gut microbiota by shifting host metabolism, emphasizing the utility of taking a more integrative approach to study diet-host-microbiome interactions.

Hereditary orotic aciduria identified by newborn screening

Introduction: Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria. Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill.

Methods: Measuring orotic acid as part of expanded newborn screening using flow injection analysis tandem mass spectrometry.

Results: Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened. The screen has identified ten Muslim Arab newborns that remain asymptomatic so far, with DBS orotic acid elevated up to 10 times the upper reference limit. Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the UMPS gene.

Conclusion: Newborn screening measuring of orotic acid, now integrated into the routine tandem mass spectrometry panel, is capable of identifying neonates with hereditary orotic aciduria.

Addition of galactose-1-phosphate measurement enhances newborn screening for classical galactosemia

Galactosemia is an inborn disorder of carbohydrate metabolism of which early detection can prevent severe illness. Although the assay for galactose-1-phosphate uridyltransferase (GALT) enzyme activity has been available since the 1960s, many issues prevented it from becoming universal. In order to develop the Israeli newborn screening pilot algorithm for galactosemia, flow injection analysis tandem mass spectrometry measurement of galactose-1-phosphate in archived dried blood spots from newborns with classical galactosemia, galactosemia variants, epimerase deficiency, and normal controls, was conducted. Out of 431 330 newborns screened during the pilot study (30 months), two with classical galactosemia and four with epimerase deficiency were identified and confirmed. Five false positives and no false negatives were recorded. Following this pilot study, the Israeli final and routine newborn screening algorithm, as recommended by the Advisory Committee to the National Newborn Screening Program, now consists of galactose-1-phosphate measurement integrated into the routine tandem mass spectrometry panel as the first-tier screening test, and GALT enzyme activity as the second-tier performed to identify only newborns suspected to be at risk for classical galactosemia. The GALT enzyme activity cut-off used in the final algorithm was lowered in order to avoid false positives.

Clinical impact of exome sequencing in the setting of a general pediatric ward for hospitalized children with suspected genetic disorders

Background: Genetic conditions contribute a significant portion of disease etiologies in children admitted to general pediatric wards worldwide. While exome sequencing (ES) has improved clinical diagnosis and management over a variety of pediatric subspecialties, it is not yet routinely used by general pediatric hospitalists. We aim to investigate the impact of exome sequencing in sequencing-naive children suspected of having monogenic disorders while receiving inpatient care. Methods: We prospectively employed exome sequencing in children admitted to the general pediatric inpatient service at a large tertiary medical center in Israel. Genetic analysis was triggered by general and/or subspecialist pediatricians who were part of the primary inpatient team. We determined the diagnostic yield among children who were referred for exome sequencing and observed the effects of genetic diagnosis on medical care. Results: A total of fifty probands were evaluated and exome sequenced during the study period. The most common phenotypes included were neurodevelopmental (56%), gastrointestinal (34%), and congenital cardiac anomalies (24%). A molecular diagnosis was reached in 38% of patients. Among seven patients (37%), the molecular genetic diagnosis influenced subsequent clinical management already during admission or shortly following discharge. Conclusion: We identified a significant fraction of genetic etiologies among undiagnosed children admitted to the general pediatric ward. Our results support that early application of exome sequencing may be maximized by pediatric hospitalists' high index of suspicion for an underlying genetic etiology, prompting an in-house genetic evaluation. This framework should include a multidisciplinary co-management approach of the primary care team working alongside with subspecialties, geneticists and bioinformaticians.

Vici syndrome in Israel: Clinical and molecular insights

Introduction: Vici Syndrome is a rare, severe, neurodevelopmental/neurodegenerative disorder with multi-systemic manifestations presenting in infancy. It is mainly characterized by global developmental delay, seizures, agenesis of the corpus callosum, hair and skin hypopigmentation, bilateral cataract, and varying degrees of immunodeficiency, among other features. Vici Syndrome is caused by biallelic pathogenic variants in EPG5, resulting in impaired autophagy. Thus far, the condition has been reported in less than a hundred individuals.

Objective and Methods: We aimed to characterize the clinical and molecular findings in individuals harboring biallelic EPG5 variants, recruited from four medical centers in Israel. Furthermore, we aimed to utilize a machine learning-based tool to assess facial features of Vici syndrome.

Results: Eleven cases of Vici Syndrome from five unrelated families, one of which was diagnosed prenatally with subsequent termination of pregnancy, were recruited. A total of five disease causing variants were detected in EPG5: two novel: c.2554-5A>G and c.1461delC; and 3 previously reported: c.3447G>A, c.5993C>G, and c.1007A>G, the latter previously identified in several patients of Ashkenazi-Jewish (AJ) descent. Amongst 140,491 individuals screened by the Dor Yeshorim Program, we show that the c.1007A>G variant has an overall carrier frequency of 0.45% (1 in 224) among AJ individuals. Finally, based on two-dimensional facial photographs of individuals with Vici syndrome (n = 19), a composite facial mask was created using the DeepGestalt algorithm, illustrating facial features typical of this disorder.

Conclusion: We report on ten children and one fetus from five unrelated families, affected with Vici syndrome, and describe prenatal and postnatal characteristics. Our findings contribute to the current knowledge regarding the molecular basis and phenotypic features of this rare syndrome. Additionally, the deep learning-based facial gestalt adds to the clinician’s diagnostic toolbox and may aid in facilitating identification of affected individuals.

Population differences in antibody response to SARS-CoV-2 infection and BNT162b2 vaccination

The concentration of SARS‐CoV‐2‐specific serum antibodies, elicited by vaccination or infection, is a primary determinant of anti‐viral immunity, which correlates with protection against infection and COVID‐19. Serum samples were obtained from 25 897 participants and assayed for anti‐SARS‐CoV‐2 spike protein RBD IgG antibodies. The cohort was composed of newly vaccinated BNT162b2 recipients, in the first month or 6 months after vaccination, COVID‐19 patients and a general sample of the Israeli population. Antibody levels of BNT162b2 vaccine recipients were negatively correlated with age, with a prominent decrease in recipients over 55 years old, which was most significant in males. This trend was observable within the first month and 6 months after vaccination, while younger participants were more likely to maintain stable levels of serum antibodies. The antibody concentration of participants previously infected with SARS‐CoV‐2 was lower than the vaccinated and had a more complex, non‐linear relation to age, sex and COVID‐19 symptoms. Taken together, our data supports age and sex as primary determining factors for both the magnitude and durability of humoral response to SARS‐CoV‐2 infection and the COVID‐19 vaccine. Our results could inform vaccination policies, prioritizing the most susceptible populations for repeated vaccination.

Expanding the Phenotypic Spectrum of GPI Anchoring Deficiency Due to Biallelic Variants in GPAA1

Background and Objectives

To expand the clinical knowledge of GPAA1-related glycosylphosphatidylinositol (GPI) deficiency.

Methods

An international case series of 7 patients with biallelic GPAA1 variants were identified. Clinical, biochemical, and neuroimaging data were collected for comparison. Where possible, GPI-anchored proteins were assessed using flow cytometry.

Results

Ten novel variants were identified in 7 patients. Flow cytometry samples of 3 available patients confirmed deficiency of several GPI-anchored proteins on leukocytes. Extensive phenotypic information was available for each patient. The majority experienced developmental delay, seizures, and hypotonia. Neuroimaging revealed cerebellar anomalies in the majority of the patients. Alkaline phosphatase was within the normal range in 5 individuals and low in 1 individual, as has been noted in other transamidase defects. We notably describe individuals either less affected or older than the ones published previously.

Discussion

Clinical features of the cases reported broaden the spectrum of the known phenotype of GPAA1-related GPI deficiency, while outlining the importance of using functional studies such as flow cytometry to aid in variant classification.

Agar Art: a CURE for the Microbiology Laboratory

We previously developed and assessed "The Art of Microbiology," a course-based undergraduate research experience (CURE) which uses agar art to spur student experimentation, where we found student outcomes related to science persistence. However, these outcomes were not correlated with specific activities and gains were not reported from more than one class. In this study, we explored which of the three major activities in this CURE-agar art, experimental design, or poster presentations-affected student engagement and outcomes associated with improved understanding of the nature of science (NOS). The Art of Microbiology was studied in three microbiology teaching laboratories: at a research university with either the CURE developer (18 students) or a CURE implementer (39 students) and at a community college with a CURE implementer (25 students). Our quasi-experimental mixed methods study used pre/post-NOS surveys and semi-structured class-wide interviews. Community college students had lower baseline NOS responses but had gains in NOS similar to research university students post-CURE. We surveyed research university students following each major activity using the Assessing Student Perspective of Engagement in Class Tool (ASPECT) survey but did not find a correlation between NOS and activity engagement. Of the three activities, we found the highest engagement with agar art, especially in the CURE developer class. Interviewed students in all classes described agar art as a fun, relevant, and low-stakes assignment. This work contributes to the evidence supporting agar art as a curricular tool, especially in ways that can add research to classrooms in and beyond the research university.

ARIC Hemostasis Study -II. Organizational Plan and Feasibility Study

In our previous paper, we reported the development of a blood collection and processing system (BCPS) suitable for the ARIC multicenter hemostasis study. As an additional step of preparation for the ARIC study, we incorporated this BCPS into an organizational plan to increase efficiency and minimize errors. We initially designed organizational trays for blood collection tubes and aliquot tubes and developed a coordinated step-by-step plan for the orderly processing of blood samples. Once the plan was considered workable, we carried out a pilot study to test the feasibility of this integrated organizational plan. Included in the pilot study were 95 healthy subjects randomly selected from 4 ARIC field centers, whose age and gender were comparable to those projected for the ARIC population. We determined the time lapse of filling the first tube as an index of blood flow. The overall mean time-lapse was 23 s (S.D. = 5). There was no significant difference among the field centers. We also determined the entire time lapse required for completing the sample processing. The total processing time was always less than 60 min. By performing the processing of samples in pairs, all the samples from two subjects could be completely processed in 70 min. This greatly increased the efficiency of field center operation. We evaluated the potential in vitro hemostasis activation by measuring plasma Β-thromboglobulin and platelet factor 4 levels. The geometric means of both proteins were comparable to our previously reported results. Fibrinogen, factor VII, factor VIII, von Willebrand factor, antithrombin III, protein C and activated partial thromboplastin time were analyzed. All the hemostatic measurements exhibited no shift of the values. We conclude that the organizational plan together with the BCPS facilitate the incorporation of hemostasis measurements into the ARIC study. It should be valuable as a general guide for other multicenter studies measuring hemostatic factors.

Childhood trauma and compulsive buying

OBJECTIVE

Childhood trauma has been empirically associated with various types of self-regulatory difficulties in adulthood. However, according to the extant literature, no study has examined relationships between various types of childhood trauma and compulsive buying behavior in adulthood.

METHODS

Using a self-report survey methodology in a cross-sectional consecutive sample of 370 obstetrics/gynecology patients, we examined five types of childhood trauma before the age of 12 years (i.e. witnessing violence, physical neglect, emotional abuse, physical abuse, sexual abuse) in relationship to compulsive buying as assessed by the Compulsive Buying Scale (CBS).

RESULTS

All forms of trauma demonstrated statistically significant correlations with the CBS. Using a linear regression analysis, both witnessing violence and emotional abuse significantly contributed to CBS scores. Further analyses indicated that race did not moderate the relationship between childhood trauma and compulsive buying.

CONCLUSIONS

Findings indicate that various forms of childhood trauma are correlated with compulsive buying behavior, particularly witnessing violence and emotional abuse.

The use of psychometrists in clinical neuropsychology: history, current status, and future directions

In recent years, the National Academy of Neuropsychology and other professional neuropsychological organizations have published a number of articles and position papers regarding the use, education, and training of psychometrists ("technicians"). Although these documents provide guidelines for the suggested qualifications and training procedures of psychometrists, none make any mention of the need for a standardized credentialing process, which is commonly required of technicians in similar fields, especially in medical settings. Given the recent changes in current procedural Terminology codes used to bill for neuropsychological services and the interpretation of legislation disallowing the use of psychometrists in New York, the need for a standard credential for psychometrists is apparent. This article will review the history and current use of psychometrists in clinical neuropsychology and highlight the need and rationale for the credentialing of psychometrists.

Sinus lift procedure of the maxilla in patients with inadequate bone for dental implants: radiographic appearance

OBJECTIVE

Dental implants have gained popularity for treating edentulism, but some patients develop jaw atrophy, which leaves insufficient bone for implants. To treat these patients, the sinus lift procedure, which augments bone, was developed. Altered anatomy from this procedure has an unusual radiographic appearance, confusing those unfamiliar with it. We describe the sinus lift procedure and its radiographic appearance.

CONCLUSION

With knowledge of this surgery and some of its pitfalls, radiographs can be more easily and accurately interpreted.

White blood cell counts in persons aged 65 years or more from the Cardiovascular Health Study. Correlations with baseline clinical and demographic characteristics

A higher white blood cell (WBC) count has been shown to be a risk factor for myocardial infarction and stroke in middle-aged populations. This study evaluated the relation between baseline WBC count and other risk factors, as well as subclinical and prevalent disease, in the Cardiovascular Health Study, an epidemiologic study of coronary heart disease and stroke in 5,201 persons aged 65 years or older. Baseline data were collected over a 12-month period in 1989-1990. WBC counts were statistically significantly higher in people with prevalent and subclinical atherosclerotic cardiovascular disease than in those who were free of disease. WBC counts correlated (p < 0.01) positively with coagulation factors, measures of glucose metabolism, creatinine, smoking, and triglycerides. In contrast, WBC counts correlated negatively with high density lipoprotein cholesterol, forced expiratory volume, forced vital capacity, and height. The correlations between WBC counts and risk factors were similar in both the entire cohort and the subgroup of persons who had never smoked. The authors conclude that WBC counts in the elderly are associated with prevalent and subclinical atherosclerotic cardiovascular disease, as well as its risk factors.

Leukocyte count correlates in middle-aged adults: the Atherosclerosis Risk in Communities (ARIC) Study

Cross-sectional associations between leukocyte count and sociodemographic and cardiovascular risk factors were investigated in 14,679 participants aged 45-64 years in the Atherosclerosis Risk in Communities Study carried out in four US communities in 1986-1989. Leukocyte count was strongly associated with present or past history of cigarette smoking and was higher in males than in females and in white subjects than in black subjects. Among never smokers, no sex differences were evident after adjustment for other risk factors. Race-associated differences were substantially reduced after other factors were taken into account in multivariate analyses. In never smokers, leukocyte count was higher in those who reported poor health, and it was inversely associated with high density lipoprotein cholesterol, forced expiratory volume at 1 second, physical activity, and, among whites, height and socioeconomic indicators. It was directly associated with indices of body weight and body fat, heart rate, blood pressure, hemoglobin, platelet count, uric acid, fasting insulin and glycemia, triglycerides, fibrinogen, antithrombin III, protein C, factors VII and VIII, and von Willebrand factor. The associations of leukocyte count with cardiovascular risk factors may either represent manifestation of subclinical disease or suggest that leukocyte count is part of the causal chain leading to atherosclerosis. Alternatively, the relation of leukocyte count to cardiovascular disease may be confounded by risk factors and thus be noncausal.

ARIC hemostasis study--II. Organizational plan and feasibility study

In our previous paper, we reported the development of a blood collection and processing system (BCPS) suitable for the ARIC multicenter hemostasis study. As an additional step of preparation for the ARIC study, we incorporated this BCPS into an organizational plan to increase efficiency and minimize errors. We initially designed organizational trays for blood collection tubes and aliquot tubes and developed a coordinated step-by-step plan for the orderly processing of blood samples. Once the plan was considered workable, we carried out a pilot study to test the feasibility of this integrated organizational plan. Included in the pilot study were 95 healthy subjects randomly selected from 4 ARIC field centers, whose age and gender were comparable to those projected for the ARIC population. We determined the time lapse of filling the first tube as an index of blood flow. The overall mean time-lapse was 23 s (S.D. = 5). There was no significant difference among the field centers. We also determined the entire time lapse required for completing the sample processing. The total processing time was always less than 60 min. By performing the processing of samples in pairs, all the samples from two subjects could be completely processed in 70 min. This greatly increased the efficiency of field center operation. We evaluated the potential in vitro hemostasis activation by measuring plasma beta-thromboglobulin and platelet factor 4 levels. The geometric means of both proteins were comparable to our previously reported results. Fibrinogen, factor VII, factor VIII, von Willebrand factor, antithrombin III, protein C and activated partial thromboplastin time were analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol screening: comparative evaluation of on-site and laboratory-based measurements

We measured cholesterol in capillary blood samples from 9683 volunteers over a four-day on-site community screening program, using the "Reflotron" desk-top analyzer (Boehringer-Mannheim Diagnostics, Indianapolis, IN). We also measured cholesterol in venous blood samples from 3% of those screened (a) with the Reflotron at the screening sites, (b) in a qualified hospital clinical laboratory, and (c) in a Centers for Disease Control standardized lipoprotein research laboratory. The sensitivity (and specificity) of the Reflotron measurements, with use of the lipoprotein laboratory measurements as the point of reference, was 0.95 (0.73) in capillary blood samples and 0.88 (0.93) in venous blood samples, compared with 0.99 (0.87) in the hospital clinical laboratory. The Reflotron measurements correlated less well with the lipoprotein laboratory values in both venous blood (r = 0.91) and capillary blood (r = 0.89) samples than did the clinical laboratory values (r greater than 0.99). Furthermore, the capillary blood measurements averaged 7% higher than venous measurements when both kinds of samples were analyzed in the Reflotron.

Cholesterol screening: comparative evaluation of on-site and laboratory-based measurements

We measured cholesterol in capillary blood samples from 9683 volunteers over a four-day on-site community screening program, using the "Reflotron" desk-top analyzer (Boehringer-Mannheim Diagnostics, Indianapolis, IN). We also measured cholesterol in venous blood samples from 3% of those screened (a) with the Reflotron at the screening sites, (b) in a qualified hospital clinical laboratory, and (c) in a Centers for Disease Control standardized lipoprotein research laboratory. The sensitivity (and specificity) of the Reflotron measurements, with use of the lipoprotein laboratory measurements as the point of reference, was 0.95 (0.73) in capillary blood samples and 0.88 (0.93) in venous blood samples, compared with 0.99 (0.87) in the hospital clinical laboratory. The Reflotron measurements correlated less well with the lipoprotein laboratory values in both venous blood (r = 0.91) and capillary blood (r = 0.89) samples than did the clinical laboratory values (r greater than 0.99). Furthermore, the capillary blood measurements averaged 7% higher than venous measurements when both kinds of samples were analyzed in the Reflotron.

Evaluation of a monoclonal immunoenzymometric assay for alpha-fetoprotein

A monoclonal immunoenzymometric assay for alpha-fetoprotein was evaluated for detection and monitoring of hepatocellular carcinoma (HCC). We studied 1343 serum specimens from 759 patients with various neoplastic and non-neoplastic diseases. The interassay CV for this assay (M-AFP) ranged from 3.5 to 5.5%, with a minimum detectable concentration of 2.2 micrograms/L, as compared with 10 micrograms/L for a polyclonal (P-AFP) RIA for AFP. The calibration curve (0-300 micrograms/L) was linear, and serum dilutions paralleled it. The reference interval (0-9 micrograms/L) was established from data on 111 healthy subjects. Regression analysis of the AFP concentration (0-300 micrograms/L) of HCC patients obtained with the M-AFP assay (y) and the P-AFP RIA (x) yielded the equation y = (1.125)x - 0.52 (r = 0.9395, n = 165), with a considerable number of discrepant results for AFP less than 100 micrograms/L. By M-AFP immunoassay, AFP was above-normal (greater than 9 micrograms/L) in most HCC patients (80%), and to a lesser extent in other liver tumors (48%). AFP was within the normal reference interval for most patients with germ-cell tumors or benign liver disease and for other disease groups. For maximum diagnostic efficiency (90%) for HCC the decision level was increased to 100 micrograms of AFP per liter. Changes in serum AFP were correlated with changes in tumor volume in most HCC patients.

Evaluation of a monoclonal immunoenzymometric assay for alpha-fetoprotein

A monoclonal immunoenzymometric assay for alpha-fetoprotein was evaluated for detection and monitoring of hepatocellular carcinoma (HCC). We studied 1343 serum specimens from 759 patients with various neoplastic and non-neoplastic diseases. The interassay CV for this assay (M-AFP) ranged from 3.5 to 5.5%, with a minimum detectable concentration of 2.2 micrograms/L, as compared with 10 micrograms/L for a polyclonal (P-AFP) RIA for AFP. The calibration curve (0-300 micrograms/L) was linear, and serum dilutions paralleled it. The reference interval (0-9 micrograms/L) was established from data on 111 healthy subjects. Regression analysis of the AFP concentration (0-300 micrograms/L) of HCC patients obtained with the M-AFP assay (y) and the P-AFP RIA (x) yielded the equation y = (1.125)x - 0.52 (r = 0.9395, n = 165), with a considerable number of discrepant results for AFP less than 100 micrograms/L. By M-AFP immunoassay, AFP was above-normal (greater than 9 micrograms/L) in most HCC patients (80%), and to a lesser extent in other liver tumors (48%). AFP was within the normal reference interval for most patients with germ-cell tumors or benign liver disease and for other disease groups. For maximum diagnostic efficiency (90%) for HCC the decision level was increased to 100 micrograms of AFP per liter. Changes in serum AFP were correlated with changes in tumor volume in most HCC patients.

Submucosal plexus and electrolyte transport across rat colonic mucosa

Electrolyte transport across two preparations of mucosa from rat colon descendens was compared to determine what influence the submucosal plexus has on electrolyte transport. One preparation consisted of the mucosa, muscularis mucosae, and the submucosal tissue and is referred to as the mucosa-submucosa preparation. The second preparation obtained by further blunt dissection of the mucosa-submucosa preparation consisted of only the mucosa and the circular muscle layer of muscularis mucosae and is referred to as the mucosa preparation. Histological studies showed that the submucosal tissue and the longitudinal layer of muscularis mucosae could be removed leaving only the mucosa and the circular layer of muscularis mucosae. The extensive neuronal network of the submucosa was shown when the submucosal tissue and longitudinal muscle layer of muscularis mucosae, which were removed, were stained histochemically for acetylcholinesterase activity. Both the mucosa-submucosa and mucosa preparations absorbed Na+ and Cl- when short-circuited. However, Na+ and Cl- absorption were significantly higher in the mucosa preparation. The increase in Na+ and Cl- transport in the mucosa preparation was accompanied with a decrease in the short-circuit current (Isc), the open-circuit potential difference (p.d.) and the transmural tissue conductance (Gt) when compared to the mucosa-submucosa preparation. Tetrodotoxin (TTX), a neurotoxin which blocks specifically the propagation of action potentials in excitable tissues, dose-dependently decreased Isc and p.d. in the mucosa-submucosa preparation when added to the serosal solution. The half-maximal effective concentration of TTX was 5 nM and maximal effective concentration 100 nM. TTX (1 microM) had no effect on Isc or p.d. when added to the mucosal solution. The decrease in Isc and p.d. caused by TTX in the mucosa-submucosa preparation was accompanied with an increase in Na+ and Cl- absorption. TTX caused only a small decrease in Isc and p.d. in the mucosa preparation. However, there was no measurable change in Na+ and Cl- transport in the mucosa preparation. The results suggest that spontaneously active neurones from the submucosal plexus have an inhibitory influence on the mucosa. Physical removal of the submucosal plexus or pharmacological blockade of the neurones within the mucosa-submucosa preparation by TTX led to enhanced absorption, suggesting that the set point of the mucosa for electrolyte transport is at or near a maximal absorptive state. Regulation or modulation of the mucosa may therefore occur by mechanisms that lower this set point, causing an inhibition of absorption of electrolytes.

Tricyclic antidepressant radioreceptor assay

A radioreceptor assay for tricyclic antidepressants described here is based on the ability of these drugs to compete with [3H]-3-quinuclidinyl benzilate (3H-QNB) for binding to muscarinic cholinergic receptors in rat brain membranes. The assay is sensitive, in that in can detect, for example, 2 ng/ml nortriptyline in plasma. Seven plasma samples from depressed patients treated with nortriptyline were assayed with the radioreceptor and gas liquid chromatographic methods, and the results from these two methods were almost identical. This assay should be used cautiously, if at all, in patients treated with other drugs that have potent anticholinergic effects.