Microscopic anatomy of the subcommissural organ in the brain of the adult greater cane rat (Rodentia: Thryonomyidae)

The subcommissural organ (SCO) is a well-developed gland present in the brain of vertebrates. The SCO secretes glycoproteins into the circulating cerebrospinal fluid and these assemble to form Reissner's fibre. It also plays an important function in neurogenesis and axonal guidance during embryogenesis. This study delves into the microscopic anatomy of the SCO in the adult greater cane rat (GCR), shedding light on its histoarchitectural characteristics. By utilizing histological techniques and microscopic analysis, we investigated the SCO's location and cellular composition within the brain of adult GCR. Our findings showed that the SCO in this species is located ventrally to the posterior commissure (PC) and dorsally to the third ventricle. The SCO consists of specialized ependymal or nuclear cell layer and apical processes lining the third ventricle. Moreover, the SCO's proximity to the PC and the third ventricle highlights its strategic position within the brain's ventricular system. With immunohistochemical analyses, the SCO cells expressed glial fibrillary protein when immunolabelled with Glial fibrillary acid protein (GFAP) antibody, a marker for astrocytes/astrocytic-like cells. Few microglia-like cells were immuno-positive for Ionized calcium-binding adapter molecule 1 (Iba1) antibody, that are existing within the SCO. However, the SCO in the GCR showed a negative immunostaining to NeuN antibody. This study contributes to our understanding of the microscopic anatomy of the SCO in a lesser-studied mammalian species. Further research into the SCO's functional significance especially during development in the GCR, may hold promise for more insights into neurological health and pathology.

Use of bispectral electroencephalogram monitoring to assess neurologic status in unsedated, critically ill patients

OBJECTIVE

To test whether spectral indices derived from the electroencephalogram (EEG), and especially the bispectral index (BIS), can be used as measures of neurologic status in unsedated, critically ill patients.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit (ICU) of a university-affiliated teaching hospital.

PATIENTS

Thirty-one awake, unsedated critically ill adults were assessed in 108 separate sessions.

MEASUREMENTS AND MAIN RESULTS

In each session, severity of illness was assessed by the Acute Physiology and Chronic Health Evaluation (APACHE III). The APACHE III Acute Physiology Score was used to quantify the degree of physiologic derangement. Neurologic function was assessed using the APACHE III Neurologic Score, the Glasgow Coma Scale, the Reaction Level Scale, and the Modified Ramsay Sedation Scale. All indices were plotted against various spectral parameters of the EEG, including BIS, an empirical index of EEG activity that is scaled from 0 to 100. BIS was significantly (p <.05) correlated with neurologic score regardless of scoring system used and was more strongly correlated than any other EEG spectral parameter. Better neurologic function was associated with higher values of BIS. In multivariate analysis, the combination of BIS and relative power in the theta band of the EEG accounted for 38% of the variability in the Glasgow Coma Scale.

CONCLUSIONS

BIS provides a reliable index of neurologic status in awake, unsedated, critically ill patients. Further research is needed to determine whether the effects of neurologic status and pharmacologic sedation upon EEG are additive, whether BIS can be used to assess pharmacologic sedation in the critically ill patient population, and whether such objective measures of neurologic status have prognostic value.

Brief diagnostic interviews (SDDS-PC) for multiple mental disorders in primary care. A pilot study

OBJECTIVE

To pilot test the feasibility and validity of new, brief, structured, physician-administered diagnostic interviews for six mental disorders in primary care patients identified from a patient-completed screen.

DESIGN

Comparison of the new diagnostic interviews with the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, version P (SCID-P), administered independently by a mental health professional.

SETTING

Three Rhode Island family practices and a South Carolina family medicine residency.

SUBJECTS

Consecutive patients of either sex, aged 18 to 70 years, who were able to read and write English were eligible for screening; 775 patients completed the screen. Of these, 246 screened positive for at least one disorder and received at least one module. Of these, 158 received a SCID-P interview.

RESULTS

The diagnostic interviews were found useful by all 16 participating physicians. Eighty-seven percent reported that they diagnosed a new mental problem, and 93% said that the modules clarified suspected symptoms. However, 26% thought the procedure was too time consuming, and 80% believed that reimbursement would be necessary for routine use. Detection of cases using the diagnostic modules was associated with physician intervention and with independent assessment of patient impairment. Over three quarters of the patients (76.4%) who were classified as positive by the physician interview for any of the diagnoses also tested positive on the SCID-P. Two thirds of the patients (62.7%) with at least one of the disorders (according to SCID-P) were classified by the physician interview as having a mental disorder. However, the operating characteristics varied across specific disorders and indicated a need for revisions and testing in larger samples.

CONCLUSIONS

These brief physician-administered diagnostic interview modules are part of a screening and diagnostic system (Symptom-Driven Diagnostic System for Primary Care [SDDS-PC], The UpJohn Co, Kalamazoo, Mich) to detect mental disorders in primary care patients. The pilot results help establish their feasibility and validity.

Development and validation of the SDDS-PC screen for multiple mental disorders in primary care

OBJECTIVE

To develop, validate, and cross-validate a patient-completed screen for multiple mental disorders in primary care.

DESIGN

Comparison of a patient self-report screen with an independent diagnostic assessment by mental health professionals using the Structured Clinical Interview for DSM-III-R diagnoses as criterion standard.

SETTING

Three Rhode Island family practices and a South Carolina family medicine residency.

SUBJECTS

In the initial validation study, 937 patients in Rhode Island were screened; 388 were interviewed. In the cross-validation study, 775 patients were screened in Rhode Island and South Carolina, and 257 were interviewed. SCREEN ITEMS: Sixty-two questions pertaining to nine mental disorders and suicidal ideation.

RESULTS

A 16-item screen remained after analysis of item and scale performance. Sensitivity, specificity, and positive predictive value, respectively, were calculated for the following scales: alcohol abuse or dependence (62%, 98%, and 54%), generalized anxiety disorder (90%, 54%, and 5%), major depression (90%, 77%, and 40%), obsessive-compulsive disorder (65%, 73%, and 5%), panic disorder (78%, 80%, and 21%), and suicidal ideation (43%, 91%, and 51%). Replication in a new sample showed attenuated but acceptable operating characteristics for cross-validation.

CONCLUSIONS

The Symptom-Driven Diagnostic System for Primary Care screen assesses multiple mental disorders that are common to primary care. It serves as a sensitive, valid, and patient-friendly first step in a new approach to recognizing and managing mental disorders in primary care. Finally, it aids the primary care clinician in selecting an appropriate diagnostic interview module for the disease for which the patient screened positive.

Absence of HIV transmission from an infected orthopedic surgeon. A 13-year look-back study

OBJECTIVE

To determine the risk of human immunodeficiency virus (HIV) transmission from an HIV-infected orthopedic surgeon to patients undergoing invasive procedures.

DESIGN

Retrospective epidemiologic follow-up study.

PARTICIPANTS

A total of 2317 former patients on whom the orthopedic surgeon performed invasive procedures between January 1, 1978, and June 30, 1991 [corrected].

MAIN OUTCOME MEASURES

HIV infection or death from an acquired immunodeficiency syndrome (AIDS)-defining tumor or opportunistic infection.

RESULTS

An orthopedic surgeon voluntarily withdrew from practice after testing positive for HIV. Testing for HIV was performed on 1174 former patients, representing 50.7% of patients on whom the orthopedic surgeon performed invasive procedures during the 13.5-year period. Patients were tested from each year and from each category of invasive procedure. All patients were HIV-negative by enzyme-linked immunosorbent assay. Two former patients reported known HIV infection prior to surgery. Review of AIDS case registries and vital records failed to detect cases of HIV infection among former surgical patients. The estimated cost of the initial patient notification and testing was $158,500. The patient notification and testing were conducted while maintaining the confidentiality of the orthopedic surgeon who was an active participant in the planning and execution of the study.

CONCLUSIONS

The risk of HIV transmission from an HIV-infected surgeon who adheres to recommended infection control practices is extremely low. Notification and HIV testing of former patients in this setting is both disruptive and expensive and is not routinely recommended.

Investigation of a staphylococcal food poisoning outbreak in a centralized school lunch program

The trend in many communities toward centralized school lunch preparation potentially increases the risk of foodborne illness. Foods often are prepared long before serving and may be distributed to satellite schools by persons with little formal training in safe techniques of food preparation or food service. In May 1990, an outbreak of staphylococcal food poisoning occurred in elementary schools in a Rhode Island community participating in such a program. In the investigation of the outbreak, students in schools that reported cases were interviewed. Food preparation, handling, and distribution were reviewed. At School E, 662 lunches were prepared and distributed to 4 additional schools (schools A-D). Schools A and B accounted for nearly all cases of the food poisoning, with rates of 47 percent and 18 percent. Eating ham increased the risk of illness (62 percent of those consuming ham and 3 percent of those who did not, relative risk = 18.0, 95 percent confidence interval = 4.0, 313.4). Large amounts of Staphylococcus aureus were cultured, and preformed enterotoxin A was identified in leftover ham. A food handler, who tested positive for the implicated enterotoxic strain S. aureus, reported having removed the casings from two of nine warm ham rolls 48 hours prior to service. Because of improper refrigeration, prolonged handling, and inadequate reheating, the ham was held at temperatures estimated at 10-49 degrees Celsius (50-120 degrees Fahrenheit) for a minimum of 15 hours. The potential for larger outbreaks prompted a statewide training program in safe food preparation for school lunch personnel, which may have applications for other communities.