Assessment of prescribing pattern of drugs and completeness of prescriptions as per the World Health Organization prescribing indicators in various Indian tertiary care centers: A multicentric study by Rational Use of Medicines Centers-Indian Council of Medical Research network under National Virtual Centre Clinical Pharmacology activity

OBJECTIVE

The rational use of medicines as per the World Health Organization (WHO) should be practiced globally. However, data regarding the completeness of the prescriptions and their rational use is lacking from developing countries like India. Thus, the aim of this study was to assess the prescribing patterns of drugs and completeness of prescriptions as per WHO core drug use and complementary indicators to provide real-life examples for the Indian Council of Medical Research (ICMR) online prescribing skill course for medical graduates.

METHODS

Prescriptions of the patients, fulfilling inclusion criteria, attending Outpatient Departments of various specialties of tertiary care hospitals, were collected by thirteen ICMR Rational use of medicines centers located in tertiary care hospitals, throughout India. Prescriptions were evaluated for rational use of medicines according to the WHO guidelines and for appropriateness as per standard treatment guidelines using a common protocol approved by local Ethics committees.

RESULTS

Among 4838 prescriptions, an average of about three drugs (3.34) was prescribed to the patients per prescription. Polypharmacy was noted in 83.05% of prescriptions. Generic drugs were prescribed in 47.58% of the prescriptions. Further, antimicrobials were prescribed in 17.63% of the prescriptions and only 4.98% of prescriptions were with injectables. During the prescription evaluation, 38.65% of the prescriptions were incomplete due to multiple omissions such as dose, duration, and formulation.

CONCLUSION

Most of the parameters in the present study were out of the range of WHO-recommended prescribing indicators. Therefore, effective intervention program, like training, for the promotion of rational drug use practice was recommended to improve the prescribing pattern of drugs and the quality of prescriptions all over the country.

543 Improving the Management of Acute Ureteric Colic in A Multi-Centre District General Hospital: A Closed-Loop Audit

Introduction

The British Association of Urological Surgeons (BAUS) released guidance in 2018 regarding the optimum management of acute ureteric colic: a condition which can present as a surgical emergency. Our aim was to review the current practice at our hospital in diagnosing and managing acute ureteric colic and ultimately, implement sustainable change to address any areas of limitations.

Method

The following data was retrospectively collected for of all patients admitted with acute ureteric colic: investigations performed, medications administered, details of surgical intervention and follow-up. 1st Cycle: March 2017 to February 2018. Intervention: Teaching sessions delivered to staff (including doctors and nurses) in the A&E and urology department. 2nd Cycle: January 2019 to December 2019.

Results

268 patients presented to A&E with ureteric colic – 18% increase from previous year. On admission: 60.4% of patients had serum calcium checked, 97.7% had a CT KUB performed within 24 hours and 67.2% were given NSAIDs; this is a 20.4%, 0.4% and 5.2% increase from the previous year, respectively. Only 31.3% of patients had an acute surgical intervention. The average wait time for clinic follow-up was reduced to 41 days following departmental education, but only 26.4% of patients were seen within the BAUS advised 4-week timeframe.

Conclusions

Re-audit showed distinct improvement in the management of acute ureteric colic. Thus, departmental education strategies have had a positive impact. It is recommended that the reservation of one daily elective theatre slot for an emergency operation and a computerised clinic booking system will further optimise our management in line with BAUS guidance.

545 Assessing the Impact Of COVID-19 On the Diagnosis and Management of Bladder Cancer in The United Kingdom – The West Midlands Experience

Introduction

The British Association of Urological Surgeons (BAUS) issued an interim strategy for the management of bladder cancer as a contingency measure during the COVID-19 pandemic. We aim to assess the actual implementation of these recommendations and deviation from the standard of care in the West Midlands.

Method

A questionnaire was devised and sent to bladder cancer leads of 12 NHS Trusts in the region in June 2020. Responses were analysed and compared with the BAUS COVID-19 strategy.

Results

11 centres were aware of the BAUS COVID-19 strategy. 2 centres were offering teleconsultations only for 2-week-wait referrals, and 6 centres had changed their practice for non-visible haematuria referrals. All centres were offering TURBTs for new and high-risk tumours. 8 centres had clear MDT documentation of NICE risk-stratifications of all bladder tumours and 10 centres were also documenting any changes in treatment. Only 7 centres continued to give BCG to newly diagnosed NMIBC. All centres continued with staging CT for newly diagnosed MIBC. Patients were still being referred for cystectomies, however few were performed. Radiation as curative and palliative intent continued. Of the 5 regional cancer centres, only 1 continued with cystectomies as normal, whereas 2 performed the procedure on a case-by-case basis, and the procedure was delayed/deferred in the other 2 centres.

Conclusions

Diagnostics, and definitive management of bladder cancer has been severely affected by COVID-19. In particular, deferred intravesical BCG and delayed radical treatment can have a dire impact on the long-term outcomes of the patients presenting during the pandemic.

370 Pure Primary Small Cell Carcinoma of the Prostate: A Rare Entity

Introduction

We report a case of small cell carcinoma of the prostate (SCCP) which is a rare, high-grade malignant neoplasm accounting for 1% of all prostate cancers (CPa).

Case

Presentation

Conclusions

SCCP metastasizes early and therefore the clinical presentation is often in an advanced stage. It is noted that there is limited value of serum PSA for SCCP diagnosis. Instead, pathological examinations and MRI rectum are vital. In terms of treatment, chemotherapy provides relief of the clinical symptoms and its use is in in accordance with the 2016 National Comprehensive Cancer Network guidelines.

644 Validation of The Prostate Imaging Reporting and Data System (PIRADS) Tool for Prostate Cancer Detection in A Contemporary British Cohort

Introduction

The European Association of Urology (EAU) recommends multiparametric MRI (mpMRI) prior to prostate biopsy for investigation of prostate cancer (CaP). Specifically, the mpMRI should be reported using the Prostate Imaging Reporting and Data System (PIRADS) tool. Our study aims to externally validate the PIRADS tool over a multi-centre district general hospital.

Method

Retrospective review was performed on 104 consecutive patients who underwent mpMRI and subsequent cognitive transrectal ultrasound biopsy of prostate (CTRUSB) over an 18-month period. Collected mpMRI data was correlated with Gleason grading obtained through CTRUSB histology.

Results

On histology findings, a total of 64.4% patients (n = 67) were found to have prostate cancer with a mean PSA density (PSAD) of 0.48. Extremes of the PIRADS scoring tool showed a clear correlation. PIRADS 2 correlated to a 0% prostate cancer detection rate (PSAD 0.16), whereas PIRADS 5 correlated to 93.1% detection rate (PSAD 0.49). However, for PIRADS 3 and 4, prostate cancer detection rates were 49.8% (PSAD 0.25) and 50.9% (PSAD 0.18) respectively.

Conclusions

Our study substantiates the association of lesions scored as PIRADS 5 with prostate cancer detection. CTRUSB in PIRADS 2 lesions can be safely avoided. For PIRADS 3 and 4 lesions, PSAD should be considered before performing a biopsy.

912 Comparison of Magnetic Resonance Imaging Cognitive Prostate Biopsy Versus Magnetic Resonance Imaging-Ultrasound Fusion Prostate Biopsy in The Detection of Prostate Cancer

Introduction

Prostate biopsy is performed to obtain tissue specimens to diagnose prostate cancer (CaP). Superimposing magnetic resonance imaging (MRI) on the prostate biopsy machine can improve the targeting of abnormal prostate lesions found on MRI scans. We compare the results of MRI cognitive prostate biopsy to MRI-US fusion biopsy in the detection of prostate cancer.

Method

Data was collected retrospectively for all patient that had an MRI and prostate biopsy from 01/01/2019 to 31/12/2019. Electronic patient records and radiology imaging software were used to collate data.

Results

319 patients with at least PIRADS 3 on MRI prostate were identified. CaP was detected in 70% (26/37) of the cognitive biopsy cohort and 66% (186/282) of the fusion biopsy cohort. None of the patients required additional biopsies. Only the fusion biopsy cohort had complications which were Urosepsis - 7, Haematuria - 3, Urinary retention - 1 and Rectal bleeding- 1.

Conclusions

Our study suggests the CaP detection rates were similar in both cohorts. However, similar patient numbers are required to avoid selection bias. 66.5% of all PIRADS 3 lesions were found to be ≥ Gleason 7. We recommend using magnetic resonance imaging-ultrasound fusion prostate biopsy to enhance prostate cancer detection rates.

648 External Validation of The European Randomized Study of Screening for Prostate Cancer Risk Calculator 3 (ERSPC-RC3) In the Detection of Prostate Cancer and Avoiding Unnecessary Prostate Biopsies

Introduction

The Prostate Cancer Research Foundation – Stichting Wetenschappelijk Onderzoek Prostaatkanker group has devised the European Randomized Study of Screening for Prostate Cancer (CaP) Risk Calculator 3 (ERSPC-RC3) tool which aims to increase prostate cancer detection rates and avoid unnecessary prostate biopsies. We report the external validation and accuracy of the ERSPC-RC3 in our UK cohort.

Method

Retrospective data was collected for patients who had prostate biopsy at a multi-centre district general hospital over an 18-month period. The ERSPC-RC3 was applied to identify the probability of a positive biopsy for CaP (Gleason score ≥7).

Results

Out of 121 TRUS biopsies, 78 patients met the ERSPC-RC3 inclusion criteria. Patients were stratified as low-risk (detectable CaP risk <12.5%) n = 10, intermediate-risk (detectable CaP risk 12.5-20%) n = 8, and high-risk (detectable CaP risk >20%) n = 60 groups. All low-risk patients had a benign histology. Gleason 7 CaP was found in 37.5% from the intermediate-risk group and 41.7% in the high-risk group respectively.

Conclusions

Our results demonstrate that using ERSPC-RC3 could have prevented 44% (n = 34) of patients from having unnecessary biopsies. We recommend the use of ERSPC-RC3 to risk stratify patients being investigated for suspected CaP.

888 Challenges in The Management of Lower Gastrointestinal Bleeding in General Surgery: Developing Consistent Practice and Application of BSG Guidelines

Introduction

Lower gastrointestinal bleeding (LGIB) accounts for 3% of all surgical referrals in the UK, with an in-hospital mortality of 3.4%. The BSG 2019 guidelines recommend risk stratification as per Oakland scoring, inpatient lower GI endoscopy for admissions and CT-angiography for unstable patients. This study evaluates the delivery of these outcomes in a district hospital setting.

Method

Retrospective audit assessing all acute LGI bleed admissions from 01-07-2019 to 28-02-2020 at Russells Hall Hospital. Shock Index (SI) and Oakland score used to stratify patients into unstable, stable-major and stable-minor LGIB. Compliance with BSG standards was assessed by review of investigations and emergent patient management.

Results

143 patients (Median age = 70years) evaluated, with 64 admissions having no formal risk stratification (OAKLAND-score) documented. Only 12 admissions underwent inpatient LGI endoscopy with sigmoid diverticulosis the most common pathology (39.3%). CT-angiogram was the initial investigation for 75% of patients admitted with unstable LGIB.

Conclusions

OAKLAND-scoring is a sensitive tool to stratify LGIB patients based on clinical parameters. Application of BSG-2019 guidelines and developing consistency in management is challenged by the lack of routine access to LGI endoscopy and tools to manage bleeding endoscopically.

Phase 1-2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine

BACKGROUND

NVX-CoV2373 is a recombinant severe acute respiratory syndrome coronavirus 2 (rSARS-CoV-2) nanoparticle vaccine composed of trimeric full-length SARS-CoV-2 spike glycoproteins and Matrix-M1 adjuvant.

METHODS

We initiated a randomized, placebo-controlled, phase 1-2 trial to evaluate the safety and immunogenicity of the rSARS-CoV-2 vaccine (in 5-μg and 25-μg doses, with or without Matrix-M1 adjuvant, and with observers unaware of trial-group assignments) in 131 healthy adults. In phase 1, vaccination comprised two intramuscular injections, 21 days apart. The primary outcomes were reactogenicity; laboratory values (serum chemistry and hematology), according to Food and Drug Administration toxicity scoring, to assess safety; and IgG anti-spike protein response (in enzyme-linked immunosorbent assay [ELISA] units). Secondary outcomes included unsolicited adverse events, wild-type virus neutralization (microneutralization assay), and T-cell responses (cytokine staining). IgG and microneutralization assay results were compared with 32 (IgG) and 29 (neutralization) convalescent serum samples from patients with Covid-19, most of whom were symptomatic. We performed a primary analysis at day 35.

RESULTS

After randomization, 83 participants were assigned to receive the vaccine with adjuvant and 25 without adjuvant, and 23 participants were assigned to receive placebo. No serious adverse events were noted. Reactogenicity was absent or mild in the majority of participants, more common with adjuvant, and of short duration (mean, ≤2 days). One participant had mild fever that lasted 1 day. Unsolicited adverse events were mild in most participants; there were no severe adverse events. The addition of adjuvant resulted in enhanced immune responses, was antigen dose-sparing, and induced a T helper 1 (Th1) response. The two-dose 5-μg adjuvanted regimen induced geometric mean anti-spike IgG (63,160 ELISA units) and neutralization (3906) responses that exceeded geometric mean responses in convalescent serum from mostly symptomatic Covid-19 patients (8344 and 983, respectively).

CONCLUSIONS

At 35 days, NVX-CoV2373 appeared to be safe, and it elicited immune responses that exceeded levels in Covid-19 convalescent serum. The Matrix-M1 adjuvant induced CD4+ T-cell responses that were biased toward a Th1 phenotype. (Funded by the Coalition for Epidemic Preparedness Innovations; ClinicalTrials.gov number, NCT04368988).

Phase 1-2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine

BACKGROUND

NVX-CoV2373 is a recombinant severe acute respiratory syndrome coronavirus 2 (rSARS-CoV-2) nanoparticle vaccine composed of trimeric full-length SARS-CoV-2 spike glycoproteins and Matrix-M1 adjuvant.

METHODS

We initiated a randomized, placebo-controlled, phase 1-2 trial to evaluate the safety and immunogenicity of the rSARS-CoV-2 vaccine (in 5-μg and 25-μg doses, with or without Matrix-M1 adjuvant, and with observers unaware of trial-group assignments) in 131 healthy adults. In phase 1, vaccination comprised two intramuscular injections, 21 days apart. The primary outcomes were reactogenicity; laboratory values (serum chemistry and hematology), according to Food and Drug Administration toxicity scoring, to assess safety; and IgG anti-spike protein response (in enzyme-linked immunosorbent assay [ELISA] units). Secondary outcomes included unsolicited adverse events, wild-type virus neutralization (microneutralization assay), and T-cell responses (cytokine staining). IgG and microneutralization assay results were compared with 32 (IgG) and 29 (neutralization) convalescent serum samples from patients with Covid-19, most of whom were symptomatic. We performed a primary analysis at day 35.

RESULTS

After randomization, 83 participants were assigned to receive the vaccine with adjuvant and 25 without adjuvant, and 23 participants were assigned to receive placebo. No serious adverse events were noted. Reactogenicity was absent or mild in the majority of participants, more common with adjuvant, and of short duration (mean, ≤2 days). One participant had mild fever that lasted 1 day. Unsolicited adverse events were mild in most participants; there were no severe adverse events. The addition of adjuvant resulted in enhanced immune responses, was antigen dose-sparing, and induced a T helper 1 (Th1) response. The two-dose 5-μg adjuvanted regimen induced geometric mean anti-spike IgG (63,160 ELISA units) and neutralization (3906) responses that exceeded geometric mean responses in convalescent serum from mostly symptomatic Covid-19 patients (8344 and 983, respectively).

CONCLUSIONS

At 35 days, NVX-CoV2373 appeared to be safe, and it elicited immune responses that exceeded levels in Covid-19 convalescent serum. The Matrix-M1 adjuvant induced CD4+ T-cell responses that were biased toward a Th1 phenotype. (Funded by the Coalition for Epidemic Preparedness Innovations; ClinicalTrials.gov number, NCT04368988).

Surgical interventions for pulmonary tuberculosis in Mumbai, India: surgical outcomes and programmatic challenges

Setting: While surgery for pulmonary tuberculosis (PTB) is considered an important adjunct for specific cases, including drug-resistant tuberculosis, operational evidence on its feasibility and effectiveness is limited. Objective: To describe surgical outcomes and programmatic challenges of providing surgery for PTB in Mumbai, India. Design: A descriptive study of routinely collected data of surgical interventions for PTB from 2010 to 2014 in two Mumbai hospitals, one public, one private. Results: Of 85 patients, 5 (6%) died and 17 (20%) had complications, with wound infection being the most frequent. Repeat operation was required in 12 (14%) patients. Most procedures were performed on an emergency basis, and eligibility was established late in the course of treatment. Median time from admission to surgery was 51 days. Drug susceptibility test (DST) patterns and final treatment outcomes were not systematically collected. Conclusion: In a high-burden setting such as Mumbai, important data on surgery for PTB were surprisingly limited in both the private and public sectors. Eligibility for surgery was established late, culture and DST were not systematically offered, the interval between admission and surgery was long and TB outcomes were not known. Systematic data collection would allow for proper evaluation of surgery as adjunctive therapy for all forms of TB under programmatic conditions.

Development of a blood based breast cancer test for Indian population

Abstract #5013

Background: The incidence of breast cancer (BC) in India is increasing as the society becomes more westernized. No national screening program exists and there is a high mortality rate which may be linked to the late detection of the disease. Here we report the development of a gene expression based blood test to detect BC. We have previously presented data from European/US cohort with accuracies ranging between 75% - 82% suggesting that test can be developed to early detect breast cancer. We now report the findings from a multi-centre study initiated to test the efficacy of the test for early detection of breast cancer (BC) in an Indian population.
 Methods: A multicentre-study was initiated where blood samples were collected from women recruited in 5 different groups 1) early stage BC, 2) late stage BC, 3) women at high risk - without BC, 4) benign breast lesions, 5) without abnormal mammographic findings. The women recruited in group 3 is a part of ongoing prospective study. Recruitment was balanced between pre- and post-menopausal women among the remaining groups. Samples were collected in PAXgene tubes and shipped to a central laboratory where RNA extraction and quality control. Gene expression analysis was performed using TaqMan® low density arrays (LDA's) containing a BC-specific gene signature in a 96-gene assay format. A total of 442 samples from groups 1, 2, 4 and 5 were used to develop the India model and estimate its prediction efficacy. The 442 samples were divided between a training cohort (N=292) and a test cohort (N=150). Gene expression data of the training cohort were used to develop the breast cancer specific diagnostic model and its performance was determined by predicting the class of the independent test cohort.
 Results: The developed model correctly predicted the class of 110/150 test samples, resulting in an overall accuracy of 73%. Prediction performance was similar for early and late stage cancer and for benign and healthy (no mammographic findings). No significant difference in diagnostic performance was seen between pre- (57/75 correctly predicted) and post-menopausal (53/75 correctly predicted) women indicating the clinical value of our test in younger women.
 Conclusion: The Indian multi-centre study demonstrates the utility of the BC-specific 96 assay signature in detecting BC in an Indian population with similar diagnostic performance seen between women with late stage (stage 2+) and early stage BC. We have previously presented data from European and US cohorts with similar diagnostic performance suggesting the broad applicability of our test. The Breast Cancer test showed the same high level of accuracy in pre-menopausal as in post-menopausal women indicating its clinical applicability in younger women where mammography is of less value due to dense breast tissue.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5013.

Granular cell tumour of the bile duct mimicking distal cholangiocarcinoma: one case report and review of the literature

Granular cell tumours (Gcts) are rare and most commonly located in the oral cavity, skin or subcutaneous tissue. The occurrence of this tumour in the biliary tract is rare. A 26 year old African man presented with abdominal pain and obstructive jaundice was found to have a localised distal bile stricture suggestive of cholangiocarcinoma which was resected by pylorus preserving partial pancreaticoduodenectomy. Histology revealed a gct of the intrapancreatic portion of the distal bile duct. GCT of the biliary tract are important as they are benign and can mimic bile duct cancers. A review of the 77 reported cases of Gcts of the biliary tract showed that the common bile duct is the most common site of occurrence (n=35). Only 2 cases in literature have been reported to be diagnosed preoperatively. Since there are no characteristic radiological features, the GCTs are difficult to differentiate from cholangiocarcinoma, sclerosing cholangitis or other benign tumors.

Is pseudophakic astigmatism a desirable goal?

PURPOSE

To determine whether pseudophakic astigmatism is a desirable goal, and if so, which one is better: against-the-rule (ATR) or with-the-rule (WTR).

METHOD

Eyes were included only if they had an uncorrected vision > or = 6/18 and N/18. Three groups, of 40 patients each were evaluated: group 1, pseudophakes with neutral astigmatism; group 2, with ATR and group 3, with WTR astigmatism Unaided distance and near visual acuity was recorded. Statistical analysis was performed using the chi-square test for independence.

RESULTS

Unaided distance vision of > or = 6/7.5 was achieved in 19 eyes (47.5%) of group 1 (neutral), 12 eyes (30%) in group 2 (ATR), and 5 eyes (12.5%) in group 3 (WTR) (p = 0.0133, significant). Unaided near vision of > or = N/9 was achieved in 17 eyes (42.5%) in group 1 (neutral), 34 eyes (85%) in group 2 (ATR), and 10 eyes (25%) in group 3 (WTR) (P < 0.001, significant). Group 1 (neutral) fared the best for unaided distance visual acuity. Group 2 (ATR) was better than in group 3 (WTR) for distant vision. Group 2 (ATR) fared the best for unaided near vision.

CONCLUSION

ATR astigmatism could be a desirable goal after cataract extraction in selected populations because the largest proportion of these cases achieved good unaided near vision with acceptable distant vision.

Paraesophageal mediastinal drainage with diversion for delayed presentation of esophageal perforation

Esophageal perforation is a serious condition; a delay of more than 48 hours in initiation of treatment leads to increased morbidity and mortality. Management of such patients is a surgical dilemma. We successfully managed 4 patients (2-iatrogenic, 1-tuberculous, 1-Boerhaave's syndrome) with delayed presentation of esophageal perforation by esophageal exclusion and paraesophageal mediastinal drainage, achieving good control of mediastinal sepsis, healing of perforation and at the same time avoiding thoracotomy and subsequent second surgery.

Isolated massive splenic peliosis

We report a patient with isolated splenic peliosis. She presented with massive splenomegaly; contrast-enhanced CT scan showed multiple hypodense, well-circumscribed shadows in the spleen. Splenectomy specimen showed multiple cysts with white fibrous walls ranging from 1-4 cm in size, containing gelatinous fluid. The patient is asymptomatic at 6 months' follow up.

Giant prosthesis for reinforcement of visceral sac for complex bilateral and recurrent inguinal hernias: a prospective evaluation

AIMS

To evaluate giant prosthesis for reinforcement of visceral sac (GPRVS) as a treatment for complex bilateral and recurrent inguinal hernias.

SUBJECTS AND METHODS

The prospective study carried out in a single surgical unit at a tertiary health care center involved consecutive series of 31 patients with complex bilateral and recurrent inguinal hernias who underwent GPRVS. All were men and the mean age was 58 years (range 49-95 years). Factors predicting high risk for recurrence included a large hernia ( greater, similar5cms, 32%, 10/31 patients), failure of one or more previous repairs (45%, 14/31 patients), chronic obstructive pulmonary disease (25%, 8/31 patients) and poor muscle tone (70%, 22/31 patients). Operative time, length of postoperative stay, complications and death were the main outcome measures.

RESULTS

Mean -/+ SEM operative time was 65 -/+ 11 minutes (range 45-115 minutes). Mean -/+ SEM length of stay was 3.5 -/+ 0.7 days (range 2-5 days). There were 4 minor complications, but no mesh infections and death. Follow up was obtained for a mean period of 14.6 months (range 12-23 months); there were no recurrences.

CONCLUSION

GPRVS provides a definitive and safe cure for repair of complex bilateral and recurrent inguinal hernias because of its simplicity, ease of the procedure, good results and low recurrence rate.

Spontaneous oesophageal perforation due to mediastinal tuberculous lymphadenitis - atypical presentation of tuberculosis

Spontaneous non-traumatic oesophageal perforation secondary to bursting of a mediastinal tuberculous abscess into the oesophagus is rare. The diagnosis is delayed, as perforation remains localised due to mediastinal lymph nodes. Patient can be effectively managed by paraoesophageal drainage of the mediastinal abscess and oesophageal diversion.

Cell interactions control the direction of outgrowth, branching and fasciculation of the HSN axons of Caenorhabditis elegans

The two serotonergic HSN motor neurons of the nematode Caenorhabditis elegans innervate the vulval muscles and stimulate egg laying by hermaphrodites. By analyzing mutant and laser-operated animals, we find that both epithelial cells of the developing vulva and axons of the ventral nerve cord are required for HSN axonal guidance. Vulval precursor cells help guide the growth cone of the emerging HSN axon to the ventral nerve cord. Vulval cells also cause the two HSN axons to join the ventral nerve cord in two separate fascicles and to defasciculate from the ventral nerve cord and branch at the vulva. The axons of either the PVP or PVQ neurons are also necessary for the HSN axons to run in two separate fascicles within the ventral nerve cord. Our observations indicate that the outgrowth of the HSN axon is controlled in multiple ways by both neuronal and nonneuronal cells.

Caenorhabditis elegans mutants defective in the functioning of the motor neurons responsible for egg laying

We have isolated and characterized 45 Caenorhabditis elegans mutants presumed to be defective in the functioning of the hermaphrodite-specific neurons (HSNs). Like hermaphrodites that lack the HSN motor neurons, these mutants are egg-laying defective and do not lay eggs in response to exogenous imipramine but do lay eggs in response to exogenous serotonin. Twenty of the 45 mutations define 10 new egl genes; the other 25 mutations are alleles of five previously defined genes, four of which are known to affect the HSNs. Seven mutations in three genes cause the HSNs to die in hermaphrodites, as they normally do in males. These genes appear to be involved in the determination of the sexual phenotype of the HSNs, and one of them (egl-41) is a newly identified gene that may function generally in sex determination. Five of the 15 genes are defined only by mutations that have dominant effects on egg laying. One gene egl(n1108), is defined by a temperature-sensitive allele that has a temperature-sensitive period after HSN development is complete, suggesting that egl(n1108) may be involved in HSN synaptic transmission. Four of the genes are defined by single alleles, which suggests that other such genes remain to be discovered. Mutations in no more than 4 of the 15 genes specifically affect the HSNs, indicating that there are few genes with functions needed only in this single type of nerve cell.

A genetic pathway for the development of the Caenorhabditis elegans HSN motor neurons

Thirty-five genes define a pathway for the development of the hermaphrodite-specific neurons (HSNs) in Caenorhabditis elegans. Some of these genes affect only one HSN trait, demonstrating that HSN migration, axonal outgrowth and serotonin expression are mutually independent events in HSN development; others, some of which are regulatory, affect multiple HSN traits. Nearly all are pleiotropic, revealing that the genes specifying HSN development also function in the development of other cell types.