Primate reaching cued by multichannel spatiotemporal cortical microstimulation

Both humans and animals can discriminate signals delivered to sensory areas of their brains using electrical microstimulation. This opens the possibility of creating an artificial sensory channel that could be implemented in neuroprosthetic devices. Although microstimulation delivered through multiple implanted electrodes could be beneficial for this purpose, appropriate microstimulation protocols have not been developed. Here, we report a series of experiments in which owl monkeys performed reaching movements guided by spatiotemporal patterns of cortical microstimulation delivered to primary somatosensory cortex through chronically implanted multielectrode arrays. The monkeys learned to discriminate microstimulation patterns, and their ability to learn new patterns and new behavioral rules improved during several months of testing. Significantly, information was conveyed to the brain through the interplay of microstimulation patterns delivered to multiple electrodes and the temporal order in which these electrodes were stimulated. This suggests multichannel microstimulation as a viable means of sensorizing neural prostheses.

The Current Role of Venous Sampling in the Localization of Endocrine Disease

Endocrine venous sampling plays a specific role in the diagnosis of endocrine disorders. In this article, we cover inferior petrosal sinus sampling, selective parathyroid venous sampling, hepatic venous sampling with arterial stimulation, adrenal venous sampling, and ovarian venous sampling. We review their indications and the scientific evidence justifying these indications in the diagnosis and management of Cushing's syndrome, hyperparathyroidism, pancreatic endocrine tumors, Conn's syndrome, primary hyperaldosteronism, pheochromocytomas, and androgen-secreting ovarian tumors. For each sampling technique, we compare its diagnostic accuracy with that of other imaging techniques and, where possible, look at how it impacts patient management. Finally, we incorporate venous sampling into diagnostic algorithms used at our institution.

Vector projection of biomagnetic fields

Biomagnetic measurements are increasingly popular as functional imaging techniques for the non-invasive assessment of electrically active tissue. Although most currently available magnetometers utilise only one component of the vector magnetic field, some studies have suggested the possibility of obtaining additional information from recordings of the full magnetic field vector. Three projection techniques were applied to different biomagnetic signals for analysis of the three orthogonal components of the vector magnetic field. Vector magnetic fields obtained from fetal cardiac activity were projected into evenly spaced directions around a unit sphere. The vector magnetic field recorded from multiple intestinal current sources with independent temporal frequencies was then projected. Finally, an external reference signal from an invasive electrode was used to project the recorded vector magnetic fields due to gastric electrical activity. In each case, it was found that the information obtained by examination of the projected magnetic field vectors gave superior clinical insight to that obtained by analysis of any single magnetic field component.

Pegvisomant: a novel pharmacotherapy for the treatment of acromegaly

Pegvisomant is a pegylated analogue of growth hormone (GH) that functions as a growth hormone receptor antagonist. Clinical trials of its use in acromegaly commenced in 1997; the drug was approved in the US in March 2003 and in Europe in November 2003. In the same year, it was made available on prescription in several European countries, with further launches due in 2004. Pegvisomant is capable of normalising serum insulin-like growth factor-I concentrations (the chief mediator of disease activity in acromegaly) in 97% of patients with active acromegaly, and therapy is associated with a significant improvement in the symptoms and signs of GH excess. Disease control is achievable with pegvisomant in patients who are wholly or partially resistant or do not tolerate somatostatin analogues; preliminary data suggest that the drug may be particularly suitable for patients with acromegaly and co-existent diabetes mellitus.

OntoDiagram: automatic diagram generation for congenital heart defects in pediatric cardiology

In pediatric cardiology as well as many other medical specialties, the accurate portrayal of a large volume of patient information is crucial to providing good patient care. Our research aims at utilizing clinical and spatial ontologies representing the human heart, to automatically generate a Mullins-like diagram based on a patient's information in the cardiology databases. Our ontology allows an intuitive way of modeling congenital defects with the structure of the human heart. A prototype system has been implemented using Protege and the Java Advanced Imaging package , and is currently under testing at the Children's Mercy Hospitals and Clinics. A pilot study showed the diagrammatical representation and characterization of congenital heart defects can be used to facilitate a better understanding of a complex congenital heart defects.

Omphalocele in three generations with autosomal dominant transmission

We report a family with nine subjects over three generations affected with an omphalocele requiring surgical intervention within the first few days of life. Because of the vertical transmission and male to male inheritance in our family, we conclude that an autosomal dominant gene caused the omphalocele in the affected family members. The paternal great grandfather of the proband was not clinically affected but produced two children with omphaloceles with different spouses.

Does a physician's ability to accurately assess the likelihood of pulmonary embolism increase with training?

PURPOSE

Pulmonary embolism (PE), an elusive diagnosis, is detected by a diagnostic work-up that is often guided by the physician's level of clinical suspicion. The ability to accurately assess PE risk on solely clinical grounds may increase with the physician's level of training. This study documented the ability of house staff practicing in an academic teaching hospital to accurately assess the clinical likelihood of PE in patients.

METHOD

During a seven-month period, all 245 patients with suspected acute PE who had had lung scans ordered via a computerized order-entry system were enrolled in the study. When ordering the lung scans, all physicians (interns, residents, and attending physicians) were required to also enter their levels of clinical suspicion on a scale of 0 to 100. The physicians' levels of clinical suspicion were correlated with the final determinations of PE, and receiver operating characteristic (ROC) curves were calculated for patients' and physicians' subgroups.

RESULTS

Attending physicians were most able to diagnose PE; residents were moderately able to make the diagnosis, and interns were least able to diagnose PE. The area under the ROC curve for a correct identification of patients with PE was greatest for attending physicians (0.839), intermediate for residents (0.601), and least for interns (0.594).

CONCLUSION

The ability to correctly assess a patient's likelihood of PE increases with a physician's level of training, suggesting that more senior physicians should be involved in the diagnostic work-up of patients with suspected acute PE. More instruction may help medical students, interns, and residents navigate clinical scenarios in which the diagnosis is uncertain or in which sequential tests must be performed to reach the correct diagnosis.

Epidemiology and clinical management of meningococcal disease in west Gloucestershire: retrospective, population based study

OBJECTIVE

To study changes in the epidemiology and management of meningococcal disease in one health district during a period of high local incidence of disease.

DESIGN

Prospective case ascertainment and data collection over 14 years, with retrospective analysis of cases.

SETTING

West Gloucestershire (population 320,000).

SUBJECTS

Residents developing meningococcal disease between 1 January 1982 and 31 December 1995.

RESULTS

252 cases of invasive meningococcal disease were identified, of which 102 (40%) were officially notified and 191 (76%) were confirmed by culture from a deep site. The observed disease incidence of 5.6/100,000/year was about 2.7 times the national incidence (as measured by either statutory notifications or reference laboratory reports). The period 1983-90 was characterised by a prolonged localised outbreak due to serogroup B serotype 15 sulphonamide resistant (B15R) strains. General practitioners gave benzylpenicillin before hospital admission to 18% of patients who presented with meningococcal disease in the first half of the study period and to 40% who presented in the second half. The overall case fatality rate was 6.7% (17/252). Four deaths were directly or indirectly related to lumbar puncture. Of 120 patients whose lumbar puncture yielded meningococci, nine (8%) showed no abnormality on initial examination.

CONCLUSIONS

Neither laboratory records nor formal notifications alone can give an accurate estimate of the incidence of meningococcal disease. Because of the dangers of lumbar puncture, the frequency of misleading negative initial findings, and the advent of new diagnostic techniques, the need for samples of cerebrospinal fluid should be critically questioned in each case of suspected meningococcal disease.

Eating in side-lying facilitates rehabilitation in neurogenic dysphagia

A 26-year-old man who had sustained a traumatic head injury aspirated when fed in the upright position. By contrast, when fed in the side-lying position swallowing improved and there was no aspiration. Implications for management are discussed.

Cephalic zoster with laryngeal paralysis

Herpes zoster reactivaction in the head and neck region is often associated with multiple cranial neuropathies, the most common one being facial paralysis. Laryngeal paralysis has also been occasionally reported with zoster infection. We present two such cases, and discuss the relevant literature on the pathophysiology, evaluation and management of this disease. Recent advances in antiviral therapy have allowed for specific medical treatment, thus making it all the more imperative to suspect zoster, even in clinically atypical cases. We suggest aggressive treatment with intravenous acyclovir for cephalic zoster complicated by vocal cord paralysis.

Short-term effects of selective renal arterial carbon dioxide administration on the dog kidney

PURPOSE

The authors examined the nephrotoxicity of carbon dioxide injected directly into the renal arteries as an arterial contrast agent.

MATERIALS AND METHODS

Fourteen anesthetized dogs received selective renal infusions of CO2 ranging from a normal dose of 7 cm3/kg to high doses of 11-54 cm3/kg. Two dogs received conventional iodinated contrast media. The effects on renal function and histologic appearance were evaluated by means of radionuclide studies (iodine-131 iodohippurate sodium and technetium-99m dimercaptosuccinate) and histopathologic examination (light, transmission, and scanning electron microscopy).

RESULTS

Although there was a mean decrease in renal blood flow of 11.86% (standard error [SE], 7.1) immediately after the injection of CO2, flow had returned to baseline (0.17%; SE, 5.27) after 24 hours. Although the sample size was small, there was no dose-dependent effect of CO2 on renal function and histologic appearance. Mild histologic changes and one case of moderate acute tubular necrosis were seen only in cases in which the kidney was positioned vertically rather than laterally.

CONCLUSION

Although formal studies in patients are required, the results of this investigation suggest that CO2 may be a safe contrast agent and less nephrotoxic than existing contrast agents, providing care is taken to ensure that CO2 is not trapped in a vertically positioned kidney, as might occur in renal transplant recipients.

A technique for displaying the entire nerve branching pattern of a whole muscle: results in 10 canine posterior cricoarytenoid muscles

There is anatomical and histological evidence for three functionally distinct muscle bellies in the canine posterior cricoarytenoid (PCA) muscle. This study attempted to define the exact nerve branching pattern to each muscle belly in 10 dogs using a modification of Sihler's neural staining technique. The results are presented here as photographs and schematic nerve maps which illustrate the following points. 1. the final terminal branches within the PCA do correspond to the three bellies of the PCA; 2. the initial nerve branch to the PCA is usually composed of multiple fascicles which rearrange before their final branching to the three bellies; 3. there is tremendous variability of the nerve branching patterns including bilateral asymmetry within the same animal; 4. the terminal branching within each belly can be surprisingly complex and contain multiple anastomoses; 5. the fast- and slow-twitch bellies of the PCA have different terminal branching patterns. These results support the functional subdivision of the canine PCA into three distinct neuromuscular compartments. This microanatomical technique appears useful for studying the basic neuromuscular organization of laryngeal muscles and their developmental and pathological changes.

Allocation of scarce resources: a challenge for American medicine

We must decide as a society how much we can afford, or at least are willing to spend, on health care as opposed to other goods. More importantly, how shall we decide which individual medical needs are to be met?

A study of the myocardial depressant factor and its relative influence in drug/alcohol mortality

A shock factor, a low molecular weight peptide, has been isolated from postmortem blood. High levels of this peptide, which depresses the myocardium, were seen in cases where drug overdose or alcoholism, or both, were the cause of death. An elevated myocardial depressant factor (MDF) level also demonstrated in a fire victim and a patient in cardiogenic shock. The peptide analysis was accomplished by using an isolated cat papillary muscle followed by paper chromatographic confirmation. Postmortem electrolytes, alcohol, and various toxic agents were eliminated as causes of myocardial depression in the isolated cat papillary muscle assay. The presence of elevated MDF levels may be significant in the overall death process.