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Biomedical subjects

S Kim

Publications and source records attributed to S Kim.

At least 1,117 records · Page 62Linked to original sources
PubMed1992

Adrenal and circulating renin-angiotensin system in stroke-prone hypertensive rats.

The plasma and adrenal renin-angiotensin system in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats were examined in animals at 5, 11, 18, and 25 weeks of age. Plasma active renin was significantly increased in 18- and 25-week-old SHRSP with impaired renal function, whereas there was no difference in the plasma prorenin level or renal renin content between the two strains at all ages examined. Thus, the rate of activation of prorenin seems to be enhanced in the kidney of SHRSP with malignant hypertension. Adrenal renin contents were severalfold higher in SHRSP than WKY rats at all ages. However, adrenal angiotensin peptides were not increased in SHRSP aged 5 and 11 weeks. In 18-week-old SHRSP, adrenal angiotensin II (Ang II) and III (Ang III) levels were fourfold and 1.8-fold higher, respectively, than in WKY rats, accompanied by 1.5-fold higher plasma aldosterone. Increased adrenal angiotensin and plasma aldosterone were also found in 25-week-old SHRSP. Zonal distribution studies indicated that the elevated Ang II and III in SHRSP were derived mainly from the capsular tissue (the zona glomerulosa). To examine the contribution of circulating angiotensin to the adrenal angiotensin content, effects of bilateral nephrectomy on adrenal angiotensin and renin were examined in 18-week-old rats. At 24 hours after nephrectomy, plasma angiotensin, prorenin, and active renin were decreased to almost negligible concentrations. Conversely, in both adrenal capsular and decapsular tissues of SHRSP and WKY rats, neither angiotensin nor renin was significantly decreased after nephrectomy. These results suggest that the increase in adrenal capsular Ang II contents in SHRSP may be partly due to an enhanced local production of Ang II.

Adrenal Glands↗
PubMed1992

Evidence for the presence of differently glycosylated forms of prorenin in the plasma of anephric man.

Previously, we unexpectedly observed that plasma inactive renin (trypsin-activatable renin) in bilaterally nephrectomized rats is not prorenin. To determine whether plasma inactive renin in anephric man is prorenin, we examined the immunological and biochemical properties of plasma inactive renin from five anephric patients. There were significant concentrations of inactive renin (5.33 +/- 2.08 ng/L.s) in plasma of anephric patients, while active renin was negligible (0.06 +/- 0.01 ng/L.s). The inactive renin from anephric patients could be immunoprecipitated 97 +/- 1% by specific antiserum against the prosegment portion of prorenin. Specific antimature renin serum completely inhibited the angiotensin-I-generating activity of inactive renin induced by trypsin treatment. The molecular mass of inactive renin from anephric patients (49.0 +/- 0 kDa), estimated by gel permeation high performance liquid chromatography, was similar to that of normal human plasma prorenin (48.2 +/- 0.8 kDa). These results indicate that plasma inactive renin in anephric man is prorenin, findings different from our previous observations obtained in anephric rats. Concanavalin-A chromatography separated inactive renin from anephric patients into three forms, including the column-unbound form, the loosely bound form, and the tightly bound form. Thus, in anephric man, differently glycosylated multiple forms of prorenin are released into the circulation from an extrarenal organ(s).

Adult↗
PubMed1992

An evaluation of prototype school-based peer counseling program.

This study reports short-term outcome evaluation results of a school-based peer counseling (PRC) program as implemented by North Forsyth High School during January 1990-February 1991. The PRC program is evaluated in terms of: 1) the content of the program as evaluated by the PRC trainees; 2) the quality of the PRC instructor as perceived by these trainees; 3) several instrumental objectives deduced from the PRC training program; and 4) the degree to which the program was able to reach other students at North Forsyth during the time the PRC was in operation. In the absence of a control group, the treatment effect of the program is determined in terms of individual growth curve models. Through the multiple evaluation designs employed in this research, it has been learned that a significantly larger proportion of students in the PRC group had more favorable attitude toward the content of the PRC program when compared to the content of what they learned from their regular school curricula. Furthermore, a significantly larger proportion of students in the PRC program reported more favorable attitude toward their instructor than their regular school teachers. The PRC program was able to elicit an improvement of trainee self-esteem (p less than .01) and their social values (p less than .05) between pre and post of the Peer Training Evaluation Instrument. In terms of client access, 18.4 percent of the totality of potential clients at North Forsyth have been reached through sixty-one peer counselors sanctioned by the school.

Adolescent↗
PubMed1992

Correlation of magnetic resonance image and histology of human teeth.

Current methods for diagnosis of pulpal pathosis are often inadequate and there is a need for an in vivo method to visualize dental pulp tissue. This report compares micromagnetic resonance imaging (MMRI) with routine H & E histology on a cross sectional view of a molar tooth. The extracted tooth was imaged with a Bruker AM-400 NMR spectrometer modified with a microimaging accessory. The tooth was then decalcified and sectioned at the same level as the MMR image. Image intensity readings were acquired for specific areas of the pulp chamber for comparison with histology. The results demonstrate that there is a close correlation between the MMRI and the low power H & E appearance of pulp tissue.

Dental Pulp↗
PubMed1992

MR imaging of acute renal cortical necrosis. A case report.

MR imaging of a patient with acute renal cortical necrosis secondary to massive bleeding following an abortion is presented. The kidneys were enlarged with a high signal intensity observed in the renal cortex on both T1- and T2-weighted images. Follow-up MR imaging showed thinned renal cortex of low signal intensity on both pulse sequences representing renal cortical calcification which was confirmed on conventional radiography and CT.

Abortion, Induced↗
PubMed1992

[Acute epidural hematoma following evacuation of chronic subdural hematoma with continuous closed system drainage].

The authors report a case of acute epidural hematoma occurring after evacuation of chronic subdural hematoma with continuous closed system drainage. Laboratory data of the patient including bleeding time were within normal limits. The cause of the postoperative intracranial hematoma was the rapid surgical decompression of the initial lesion, and we considered that it could be prevented if chronic subdural hematoma was treated using closed system drainage and slow decompression. But acute epidural hematoma occurred after this operative procedure and it was accelerated by evacuation of the chronic subdural hematoma through the drain. An emergent craniotomy and removal of the hematoma was performed, so the patient was discharged from hospital with satisfactory neurological recovery. A careful check of the evacuated hematoma volume is very important, and CT scanning should be immediately performed if postoperative hematoma is suspected.

Acute Disease↗
PubMed1992

Reassessment of preoperative laboratory testing has changed the test-ordering patterns of physicians.

To test the hypothesis that physicians have substantially reduced the ordering of unwarranted preoperative tests, the authors reviewed 2,093 medical records of patients having four surgical procedures performed at three institutions in three cities in 1979, 1981, 1983, 1985 or 1987. Excluding hemoglobin measurements, the incidence of ordering preoperative laboratory tests unwarranted by findings on history or physical examination decreased from 32.2 to 25.9 percent during this decade, representing a 19.6 percent reduction. This decrease was irregular and varied from operation to operation, test to test and institution to institution. Overall, the percentage of preoperative tests ordered that were unwarranted decreased from 66.9 percent in 1979 to 60.1 percent in 1987. Extrapolating these results, the authors estimate that more than $320 million was saved annually by elimination of unwarranted tests and that the potential savings could exceed $1.35 billion a year. Unexpectedly, the preoperative ordering of medically indicated tests also decreased (from 92.9 to 80.9 percent, representing a 12.9 percent reduction). Because the benefit of performing justified tests is probably greater than the benefit of avoiding unwarranted tests, the net change has probably not been beneficial. A better system for obtaining justified tests and for eliminating the unwarranted tests may be necessary before a net benefit occurs. Punitive measures to reduce testing without prior establishment of such a system may save money, but impair health.

Chicago↗
PubMed1992

Acute renal failure secondary to rhabdomyolysis. MR imaging of the kidney.

MR imaging of the kidney was performed in 6 patients with acute renal failure (ARF) secondary to rhabdomyolysis caused by snake bite (n = 4), crush injury (n = 1), and carbon monoxide poisoning (n = 1). A test for urine myoglobin was positive in all 6 patients and MR imaging was done 6 to 18 days after the causative event of the rhabdomyolysis. MR images in all 6 patients showed globular swelling of the kidneys, preserved corticomedullary contrast on T1-weighted images, and obliteration of corticomedullary contrast on T2-weighted images. Unlike other medical renal diseases in which corticomedullary contrast is lost on T1-weighted images, preservation of the corticomedullary contrast on T1-weighted MR images with globular renal swelling was a constant finding in patients with ARF secondary to rhabdomyolysis.

Acute Kidney Injury↗
PubMed1992

Pharmacokinetic study of intraperitoneal streptozotocin.

Streptozotocin, a nitrosourea, has limited antitumour activity. However, in concentrations and exposures higher than those achieved after intravenous dosing, streptozotocin has been reported to sensitize various cell lines in vitro to other nitrosoureas or alkylating agents. We hypothesized that the intraperitoneal administration of streptozotocin would achieve concentrations and exposures in the peritoneal cavity sufficient for this sensitization to take place. The pharmacokinetics of streptozotocin in the peritoneal cavity and in plasma were determined in patients who received 1 g of streptozotocin via the intraperitoneal route. Fifteen courses were administered to 12 patients. The mean total area under the concentration versus time curves (AUC) was 183 +/- 31 (SE) mM min in the peritoneal cavity (5 courses) and 5.3 +/- 1.1 (SE) mM min in plasma (6 courses). The mean peritoneal to plasma AUC ratio was 64 +/- 23 (5 courses). The mean peak streptozotocin concentrations in the peritoneal cavity (5 courses) and plasma (6 courses) were 1.9 +/- 0.4 mM and 0.03 +/- 0.01 mM, respectively. No significant toxicity was observed on any course. We conclude that intraperitoneal administration of streptozotocin is feasible, and that drug concentrations and exposures are in an appropriate range in the peritoneal cavity to cause sensitization to other nitrosoureas.

Adult↗
PubMed1992

Effects of CO2 laser irradiation on pulpal blood flow.

CO2 laser may be beneficially applied to teeth in preventive and restorative dentistry, but its physiopathologic effects on the dental pulp have not been reported. To address the dynamic pulpal changes induced by CO2 laser the purpose of this study was to examine such changes in pulpal microcirculation. The enamel surfaces of 4 cat canines were irradiated by CO2 laser beam, delivered by either a handpiece or microslad with a focal spot diameter of 0.21mm and 0.33mm, respectively. Exposure powers of 2.6-20 W were used for durations of 0.05-0.2 sec, resulting in energy density range of 304-1440 J/cm2. Non-invasive measurement of pulpal blood flow (PBF) by a laser Doppler flowmeter was maintained continuously before and following CO2 laser irradiation. CO2 laser irradiation resulted in an immediate increase in PBF, which subsided after 2-3 min. Large pulps responded with a significantly higher PBF increase than small pulps. These results confirm that CO2 laser irradiation of the tooth surface has a thermal effect on the pulp, which is moderated by the insulating capability of dentin. It appears that the associated thermal damage is not extensive when laser exposure parameters are such as used herein.

Animals↗
PubMed1992

Effects of selected inflammatory mediators on blood flow and vascular permeability in the dental pulp.

One of the major events involving inflammatory processes is the alteration of microcirculatory hemodynamics by inflammatory mediators released from tissue components. Using modern macrocirculatory techniques, 15 mu radioisotope labeled microspheres, 133Xe washout, laser Doppler flowmetry and double isotopes, 125 and 131I-albumin, and microcirculatory methods, intravital fluorescence microscopy with FITC labeled dextran, we have examined the effects of selected mediators, e.g. 5-hydroxytryptamine (5-HT), prostaglandin E2 (PG-E2), bradykinin (BK), substance P (SP), calcitonin gene related peptide (CGRP) and histamine on blood flow and vascular permeability in the pulp of experimental animals. Surprisingly, SP and CGRP caused weak albumin leakage in the pulp, while the opposite is true in high compliance tissues, such as muscles, suggesting that the vessels in a low compliance environment, such as the pulp, may not be as permeable in response to selected mediators. Intraarterial injection of 5-HT caused a strong vasoconstriction which was mediated by 5-HT1p receptor subtype. The pulpal 5-HT receptor subtype was identified by immunocytochemistry, receptor autoradiography and functional investigations. Intravital fluorescence microscopy observations of the rat incisor preparation showed that histamine, BK and PGE2 increased permeability, whereas isoproteranol caused partial inhibition of the BK-induced increase. In an induced pulpal inflammation model using plaque extract, blood flow increased over 40% in the moderately inflamed pulp, which demonstrated severe vasodilation and polymorpholeukocyte accumulation. In the partially necrotic pulp, blood flow decreased nearly 35%. Results of this study clearly show that there is a high structural/functional correlation in pulpal microcirculation in inflammation. As demonstrated in this presentation, the effects of inflammatory mediators on pulpal microcirculatory hemodynamics are complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The role of selected cations in the desensitization of intradental nerves.

Dentinal sensitivity is a common complaint of patients. Removal of cementum or enamel leaves the dentin exposed allowing various stimuli to produce fluid movement through the dentinal tubules. These fluid movements are believed to activate pulpal sensory nerves leading to pain. Various therapeutic approaches have been investigated to treat this problem. Resins, fluoride compounds and oxalate solutions have been used to block the dentinal tubules. KNO3 and SrCl2 are active ingredients in desensitizing tooth pastes but neither compound reduces the permeability of dentine. The ability of various solutions to decrease hypertonic (3M NaCl) evoked nerve activity was tested in the canine teeth of anesthetized cats. Excitatory and desensitizing solutions were placed into a deep dentinal cavity prepared over the incisal pulp horn. An electrode used to record nerve activity was also placed into this deep cavity. KNO3 and other K+ ion containing solutions elicit a biphasic effect on nerve activity. Immediately following application of these solutions into the deep dentinal cavity there is a brief burst of high frequency spike activity. Following this brief period of excitation, the intradental nerves are silent and respond weakly to hypertonic NaCl. CaCl2 and other divalent cation solutions also inhibit hypertonic NaCl induced nerve activity, but have a weaker effect than that exerted by K+. These observations can be explained based on the effects of various ions on nerve excitability. Increasing the K+ ion concentration in the vicinity of the dentinal nerve terminal depolarize and activates the nerve fibers. Following a prolonged period of depolarization the action potential mechanism is inactivated. Divalent cation solutions stabilize the nerve membrane without changing the membrane potential. Desensitizing solutions do not decrease nerve activity by an effect on pulpal blood flow. This experimental model does not entirely explain the clinical action of these desensitizing agents. The role of inflammation in hypersensitivity and dental pain is currently being investigated.

Animals↗
PubMed1992

The effects of capsaicin on pulpal blood flow.

One of the initial events in pulpal inflammation has been characterized as neurogenic inflammation: the release of neuropeptides following excitation of sensory C-fibers by noxious stimuli which alters microcirculatory parameters, that is, vasodilation and plasma extravasation. Thus, the purpose of the study was to investigate the effect of capsaicin on pulpal blood flow (PBF) with the aim of understanding neurogenic inflammation in the dental pulp by characterizing the response of the pulpal vasculature to repeated applications of various concentrations of capsaicin. Experiments were performed on canine teeth of cats anesthetized with sodium pentobarbital. PBF was measured by the laser Doppler flowmeter following the application of capsaicin into the dentinal cavities of the canine teeth. The increases of PBF to capsaicin were 31.8 +/- 6.3% (n = 6) and 54.2 +/- 6.2% (n = 9), for 1 microM and 100 microM capsaicin, respectively. The increase of PBF peaked at about 50 sec after the capsaicin placement and the PBF returned to control level within 20 min following capsaicin removal. Four repeated applications of 1 microM capsaicin caused a small change in the peak PBF amplitude. In contrast, a second application of 100 microM capsaicin caused a significantly smaller increase of PBF than the first application (26.8 +/- 6.4% vs. 54.2 +/- 6.2%). Results of the present study show that local application of capsaicin caused the increase of PBF and that repeated capsaicin stimulations inhibited PBF responses. Smaller PBF increases in response to high concentrations of capsaicin also suggested the depletion of vasoactive substances, e.g. substance P, from the sensory nerve terminals, which appears to be dose-dependent. The PBF response to capsaicin suggests that neurogenic inflammation in the dental pulp involves capsaicin-sensitive nerve endings.

Animals↗
PubMed1992

Functional alterations in pulpal microcirculation in response to various dental procedures and materials.

Using the quantitative 15 microns microsphere injection method, the effects of several restorative procedures on pulpal microcirculation in dog canine teeth were investigated. Pulpal blood flow (PBF) decreased steadily as the remaining dentin thickness (RD) became smaller with crown preparation without water spray. One hour after the preparation wit 1/3 RD (approximately 1 mm) PBF was reduced to 10% of the control, indicating that dry deep preparation has a deleterious effect on PBF. A careful preparation to an RD of 1 mm under copious water spray had a negligible effect on PBF. Dry preparation to an RD of more than 50%, on the other hand, caused a significant increase in blood flow through shunt vessels, AVAs and "U"-turn loops as determined with the 9 microns and 15 microns microspheres. These shunt vessel activities were especially prominent in the apical portion of the pulp, suggesting that the activation of the shunt vessels may be one of the compensatory mechanisms of the pulp in response to inflammation. In rat incisor teeth observed by intravital microscope, shunt vessels opened up as the incisor tips were drilled. Impression procedures after tooth preparation with water spray using the copper band with wax caused severe flow fluctuation as compared to rubber base material impression. In anesthetics, the use of epinephrine was found to be the single most important factor affecting pulp circulation. Whether it is by infiltration or mandibular block, the use of epinephrine containing anesthetic caused a severe reduction in PBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗