Biomedical subjects

R L Rhoten

Publications and source records attributed to R L Rhoten.

5 recordsLinked to original sources

PubMed1998

Vascular and glomerular expression of endothelin-1 in normal human kidney.

To understand better the function of endothelin-1 (ET-1) in renal physiology, we examined vascular and glomerular expression of ET-1 in normal human kidney and in lupus nephritis. Immunohistochemical analysis revealed that renal endothelium of glomeruli, arteries, veins, and capillaries expressed ET-1. Endothelial cells were the principal source of glomerular ET-1; positive immunostaining was detected only rarely in mesangial cells and vascular smooth muscle cells from normal kidney. However, mesangial staining for ET-1 was elevated in patients with lupus nephritis, suggesting that under certain conditions mesangial cells elaborate ET-1. Indeed cultured human mesangial cells from normal subjects secreted ET-1 peptide. ET-1 secretion was augmented by the protein kinase C activator phorbol ester and by transforming growth factor-beta1 (TGF-beta1), a cytokine implicated in the development of glomerulosclerosis. Transient transfection of cultured mesangial cells with a preproET-1 reporter construct showed that the preproET-1 promoter is transcriptionally active in mesangial cells and is stimulated by TGF-beta1, phorbol ester, or ectopic expression of protein kinase beta1. Cultured human mesangial cells have both ETA and ETB receptors that contribute to ET-1-stimulated mitogenesis. Taken together, these results demonstrate that ET-1 is expressed at sites where paracrine or autocrine signaling by ET-1 might control renal vasoconstriction, glomerular filtration rate, and remodeling of the glomerulus in renal disease.

Cells, Cultured↗

PubMed1997

Transnasal transseptal endoscopic approach to the sphenoid sinus.

A modified transseptal approach to the sphenoid sinus and pituitary gland utilizing rigid endoscopy has been developed by the Departments of Otolaryngology, Plastic Surgery, and Neurosurgery at The Cleveland Clinic Foundation. When compared with alternate approaches or the nonendoscopic transseptal procedure, the modified approach provides better visualization and increased illumination of the surgical sites. Other advantages include a decrease in operating time, dissection, bleeding, and postoperative morbidity without compromising nasal function in the postoperative period.

Adenoma↗

PubMed1997

Computer-assisted endoscopy for neurosurgical procedures: technical note.

OBJECTIVE: As neuroendoscopy technology evolves, the ventriculoscope is playing a greater role in the diagnosis and treatment of disorders affecting the ventricular system. However, even with direct visualization, correctly orienting and safely navigating an endoscope may be difficult with abnormal anatomy, in small ventricles, or when searching for small periventricular lesions identified on neuroimaging studies. The ability to define the location of the endoscope during such procedures enhances its effectiveness and safety. INSTRUMENTATION: We report the successful adaptation of an image-guided stereotactic wand to a rigid neuroendoscope. With computer-assisted neuroendoscopy (CANE), the tip position and orientation of a rigid ventriculoscope were visualized in real-time on neuroimaging studies that were obtained before surgery. Because computer guidance may also be used with the neuroendoscope obturator during ventricular access, uncertainty in accessing small ventricles is minimized. RESULTS: Eleven patients were operated on at The Cleveland Clinic Foundation using the CANE system. All patients except one were improved after surgery. Early experience suggests that CANE is useful for certain endoscopic procedures by aiding in trajectory planning, ventricular navigation, and localizing certain pathological conditions. CONCLUSION: Even with direct visualization, ventriculoscopy in abnormal anatomy may be difficult. Although the CANE system may not always be necessary in neuroendoscopy, correlation of the endoscope tip location, with an intraoperative magnetic resonance image via continuous computer updates, may enhance the safety, as well as the efficiency, of neuroendoscopy in the future.

Adolescent↗

PubMed1997

Specific repression of the preproendothelin-1 gene in intracranial arteriovenous malformations.

Cerebrovascular arteriovenous malformations (AVMs) display abnormal vascular development and dysautoregulation of blood flow. Genetic mechanisms that contribute to the pathogenesis and phenotype of cerebral AVMs are unknown. As a first step in understanding the pathophysiology of AVMs, the authors investigated the hypothesis that endothelial dysfunction-specifically, deregulation of endothelin-1 (ET-1) secretion-contributes to the abnormal vascular phenotype and the lack of hemodynamic autoregulation elaborated by these lesions. Endothelin-1 peptide and preproendothelin-1 (ppET1) messenger RNA were not detected in the intranidal vasculature of all 17 patients with AVMs studied, but were prominently expressed in human control subjects with normal cerebrovasculature (p < 0.01). Although AVM vasculature lacked ET-1, its expression was prominent in vasculature distant from these lesions, suggesting local repression of the ppET-1 gene. Local repression of ET-1 was specific to AVMs; ET-1 in vascular malformations of patients with Sturge-Weber disease was actually elevated compared to normal controls (p < 0.01). Repression of the ppET-1 gene was an intrinsic phenotype of AVM endothelial cells and was not due to factors in the AVM microenvironment. The authors also showed that ETA receptor expression was low in AVM vasculature compared to normal controls. Together, these results demonstrate that the ppET-1 gene is locally repressed in AVM lesions and suggest a role for abnormal ppET-1 gene regulation in the pathogenesis and clinical sequelae of cerebral AVMs.

Adolescent↗

PubMed1995

Antibiotic penetration into cervical discs.

Antibiotics are frequently prophylactically administered in surgical procedures to reduce the incidence of infection. The penetration of antibiotics into lumbar discs has been studied with mixed results, but penetration into cervical discs has not been reviewed. In this study, we examined the penetration of two commonly used antibiotics, oxacillin and cefazolin, into cervical discs. Eighteen patients with a total of 30 discs removed were studied. Two groups, each consisting of four patients with five discs removed, received either 1 g of oxacillin or 1 g of cefazolin by a single, preoperative intravenous infusion. Two other groups, each consisting of five patients with 10 discs removed, received either 2 g of oxacillin or 2 g of cefazolin, also by a single, preoperative intravenous infusion. A blood specimen, from which serum antibiotic levels were determined, was obtained from each patient simultaneously with each discectomy. The time interval between the antibiotic infusion and discectomy/phlebotomy was also recorded. Antibiotic levels were detected in all discs removed but were quantifiable in only 12. Nine of these 12 had been exposed to cefazolin. Of these nine discs, one was from a patient who had received 1 g whereas the other eight were from patients who had received 2 g of cefazolin. This represents 80% of the removed discs exposed to 2 g of cefazolin (10 discs total) and 20% exposed to 1 g (5 discs total). The remaining three discs with quantifiable antibiotic levels had been exposed to 2 g of oxacillin, which represents 30% of the discs (10 total) exposed to that dose of oxacillin. Although cervical disc space infections are rare, they are serious.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗