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Biomedical subjects

R P Miller

Publications and source records attributed to R P Miller.

At least 19 recordsLinked to original sources
PubMed1992

Bilateral choanal atresia associated with malformation of the anterior skull base: embryogenesis and clinical implications.

A number of craniofacial and systemic malformations have been described in association with choanal atresia. We report a case of bilateral choanal atresia associated with congenital absence of the cribriform plate, crista galli, and perpendicular plate of the ethmoid bone. The anterior skull base defect was detected by using high-resolution computed tomography with three-dimensional reconstructions. The findings support the mesodermal flow theory of choanal atresia, in which there is excess migration of neural crest cells into the developing nasal septum and posterior choanae. This occurs at the expense of cells that would otherwise form the rest of the ethmoid complex. Clinical implications include the need for adequate preoperative imaging of the anterior skull base and consideration of potential intracranial complications during surgical repair.

Abnormalities, Multiple↗
PubMed1991

Incidence of perforation with Goode T-tube.

Two groups of patients from the same era were retrospectively studied in Cincinnati and Chicago. In Cincinnati two subgroups were studied. The first group received myringotomy with insertion of a 'T'-shaped ventilating tube (75 patients, 140 ears, 147 insertions). Fifty-eight ears still had the tube in place, 31 had healed after spontaneous extrusion, 17 had healed after removal of the tube, 20 had persistent perforation after the tube was gone, 2 had a cholesteatoma, and 4 patients (7 ears) were lost to follow-up. The second set received myringotomy and insertion of a small grommet (Donaldson tube, 71 patients, 140 ears, 164 insertions) tympanostomy tube. None could be documented to still have the tube in place, 156 ears healed after spontaneous extrusion, none required removal, 3 ears had a persistent perforation after the tube was gone, none had cholesteatoma, and 5 patients (5 ears) were lost to follow-up. The perforation rate for the T-tube is 13.6% and for the grommet is 1.8% (P = 0.0005). In Chicago, 93 patients who received the Goode T style tube (175 ears, 175 insertions) prior to March, 1986 were evaluated. The degree of retraction of the tympanic membrane preoperatively was recorded. No ears still had the tube in place, 145 had healed after spontaneous extrusion or removal of the tube, 30 had persistent perforation 12 months after the tube was gone, 4 had a cholesteatoma, and 8 patients (15 ears) were lost to follow-up. The rate of perforation is 18.8% which is not statistically different from the Cincinnati rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Chicago↗
PubMed1979

Long acting cAMP analogues enhance sulfate incorporation into matrix proteoglycans and suppress cell division of fetal rat chondrocytes in monolayer culture.

The relationship between replication and the synthesis of matrix sulfated proteoglycans was investigated with fetal rat chondrocytes grown in monolayer culture. The effect of N6 O2' dibutyryl adenosine 3', 5' cyclic monophosphate (DBcAMP), adenosine 3', 5' cyclic monophosphate (cAMP), 8 Bromo adenosine 3', 5' cyclic monophosphate (8 Br-cAMP), sodium butyrate and hydroxyurea was examined. Between 0.05 and 0.5 mM DBcAMP, a dose related inhibition of cell division and stimulation of [35SO=/4] incorporation into matrix proteoglycans was demonstrated. At the higher concentrations of DBcAMP, cell division was completely inhibited and the enhancement of [35SO=/4] incorporation into matrix proteoglycans ranged between 40 and 120% (P less than 0.01). Utilizing 14C-glucosamine and photometric determination of proteoglycans with Alcian Blue, it was demonstrated that the increase in sulfate incorporation reflected enhanced accumulation of extracellular matrix. The effects of DBcAMP were mimicked by 8 Br-cAMP, suggesting they were mediated by the adenylyl cyclase system. cAMP (0.05-0.5 mM), sodium butyrate (0.1-0.5 mM) and hydroxyurea (0.5-5 mM) partially or fully inhibited cell division, but either failed or only slightly enhanced sulfate incorporation. The enhanced sulfated proteoglycan deposition promoted by DBcAMP began 8 to 12 hours after serum stimulation, its onset occurred prior to thymidine incorporation and the effect persisted for 28 hours. Determination of cell volume demonstrated an increase in size of DBcAMP treated chondrocytes between 8 to 12 hours, coincident with the onset of increased sulfate incorporation. These results are consistent with a model where matrix sulfated proteoglycan deposition by chondrocytes is mediated by intracellular cAMP levels and occurs in the G1 phase of the cell cycle.

Animals↗
PubMed1979

Insertion of Gibbons ureteral stents using endourologic techniques.

We describe our technique for the antegrade insertion of the redesigned Gibbons ureteral stent. We have used this technique for 19 kidneys without failures or complications. The advantages of internal drainage and of antegrade stent placement are discussed.

Catheters, Indwelling↗
PubMed1979

Percutaneous U-loop nephrostomy.

Single-tube nephrostomy drainage can be converted to U-loop drainage using percutaneous methods. Because only local anesthesia is required the technique can be used for patients who are poor operative risks.

Humans↗
PubMed1979

Controlled ureteral meatotomy.

An endourologic technique for a safe and adequate ureteral meatotomy has been devised. The ureter is catheterized anterograde through a percutaneous nephrostomy and a controlled ureteral meatotomy is done with a modified ureteral catheter. A silicone splint is then placed. The technique is safer than other techniques because repeated, more proximal incisions can be made and because the splint and proximal urinary division will prevent extravasation.

Aged↗
PubMed1979

Cooling towers and evaporative condensers.

By 31 October 1978 there had been four confirmed instances where the Legionnaires' disease bacterium had been isolated from water samples taken from cooling towers or evaporative condensers located near the site of an epidemic of Legionnaires' disease. These devices are widely used to reject unwanted heat into the atmosphere and vary greatly in size and configuration. However, the operation of all towers and condensers depends on intimate contact between the circulating water and ambient air. Airborne contaminants in the vicinity of these devices are likely to be absorbed to some degree by the circulating water. The airstream leaving a cooling tower is saturated with water vapor and may also contain a relatively minute portion of the circulating water in the form of fine droplets known as drift. It is common practice to bleed a small portion of the circulating water, including all contaminants, from the tower into a storm sewer, sanitary sewer, or even a nearby body of water.

Aerosols↗
PubMed1979

Development of a research program in a community teaching hospital.

Affiliation between community hospitals and university centers has become a prominent trend. St Mary's Hospital, a 298-bed community hospital, affiliated with the University of Rochester, School of Medicine and Dentistry, and in five years developed an academic program. The strategies we utilized included the following: (1) definition of the number of specialists needed for the hospital's patient population; (2) development of specific subspecialty units with more than one member with the primary intent of fostering an investigative program; (3) analysis of total projected faculty salary and laboratory renovation and equipment costs to allow staged development of the program; (4) design of a flexible research areas; and (5) joint use of equipment and space with the Clinical Laboratory Service. The program was financed through third-party reimbursement, faculty-generated Department of Medicine funds, gifts by private patrons, and extramural grants. At a time of diminishing investigative support, a medium-sized community hospital can develop a research program.

Academic Medical Centers↗
PubMed1978

Introduction of the Gibbons ureteral stent facilitated by antecedent percutaneous nephrostomy.

Patients in whom retrograde catheterization of the ureters has failed can have the Gibbons catheter placed by a new technique that requires no regional or general anesthesia. This technique entails antecedent percutaneous nephrostomy and passage of an angiographic catheter down the ureter. The catheterizing apparatus is attached to the angiographic catheter and then pulled into position.

Humans↗
PubMed1978

Extraction of ureteral calculi from patients with ileal loops: a new technique.

A technique is described by which calculi can be removed from the distal ureters of patients with ileal conduit urinary diversions. A percutaneous nephrostomy is done and an angiogram catheter is manipulated down the ureter past the obstruction. After the angiogram catheter is retrieved from the loop with a Bumpus forceps a stone basket is attached, pulled up the ureter and opened. The stone can then be captured under fluoroscopic control and, by replacing the stone basket with a silicone splint, the ureteroileostomy also can be splinted. This may be important particularly if there is extravasation from the ureteroileostomy after stone manipulation or operation.

Aged↗
PubMed1977

Enhancement of [3H-methyl]thymidine incorporation and replication of rat chondrocytes grown in tissue culture by plasma, tissue extracts and vasopressin.

A pituitary mitogenic peptide, which stimulates cellular replication of a variety of cells maintained in tissue culture, has been identified by other investigators. To study this mitogenic substance, we developed an assay to measure mitogenic substances utilizing fetal rat chondrocytes grown in monolayer culture. Mitogenic activity of added test substances was determined by [3H-methyl]thymidine incorporation into trichloroacetic acid insoluble cell products and increase in total cell number after 24 h exposure. Extracts of whole pituitary glands were more potent in stimulating these cellular indices than either those of liver or muscle, confirming that the chondrocytes are sensitive to the described mitogen. Identically prepared extracts of either anterior or posterior pituitary lobes were mitogenic indicating the presence of two or more mitogenic substances in crude pituitary extracts. Synthetic lysine vasopressin and a beef pitressin concentrate stimulated thymidine incorporation into chondrocytes in the absence of calf serum and this effect was additive to that of calf serum, suggesting that the mitogenic substance of posterior pituitary extracts was vasopressin. The maximum effective dose of vasopressin leading to an increase in either thymidine incorporation or total cell number was between 100 to 500 pg/ml, and as little as 50 pg/ml of hormone elicited an increase in total cell number. The mitogenic effect of both vasopressin and calf serum on chondrocytes was partially inhibited by 1 X 10(-4)M N, O'dibutryl cyclic adenosine 3',5' monophosphate suggesting that cell division of chrondrocytes may be under tonic control by the andenylyl cyclase system. We conclude that vasopressin is a potent mitogen for chondrocytes maintained in tissue culture and its presence must be rigorously excluded in evaluating mitogenic activity of pituitary or serum concentrates.

Animals↗
PubMed1976

Acetaminophen elimination kinetics in neonates, children, and adults.

The elimination of acetaminophen (APAP) following an oral dose of 10 mg/kg in newborn infants, children, and adults was compared. Urinary excretion of unchanged APAP, APAP-sulfate, and APAP-glucuronide was complete within 30 hr at all ages. Higher percentages of the dose were excreted in the urine as APAP-sulfate in neonates (0-2 days old) and children (3-9 yr old) than in 12-yr old children and adults. A pharmacokinetic analysis indicated that the higher rate of APAP-sulfate formation in younger age groups apparently compensated for a deficiency in glucuronide formation. No dramatic age-related differences in the overall elimination rate constant for APAP were observed despite the quantitative changes in the metabolic pathways during early childhood.

Acetaminophen↗
PubMed1976

Disposition of nicotine in the rat after intravenous administration.

The pharmacokinetics of 14C-labeled nicotine were studied in male Fischer-344 rats following the i.v. administration of a single 0.8 mg/kg dose. Serial blood samples were collected and the nicotine in plasma was separated from its metabolites by TLC. The levels of radioactivity corresponding to nicotine, cotinine, and polar metabolites remaining at the origin of the chromatogram were determined by liquid scintillation counting. Plasma nicotine concentration was characterized by a biexponential decay with a mean biologic half-life (t1/2) of 0.96 hrs, a large apparent volume of distribution (5.67 L/kg) and total body clearance (4.04 L/hr/kg). Maximum plasma concentration of cotinine was reached within 1 1/2 hrs post-nicotine administration, followed by a monoexponential decline with a mean t1/2 of 6.4 hrs. The plasma concentrations of origin activity rose to maximum levels within 30 minutes and declined slowly in a biexponential fashion with a mean t1/2 of 23.2 hrs. It appears, therefore, that while nicotine is rapidly eliminated, its metabolites persist in the plasma a long time after its administration.

Animals↗