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Biomedical subjects

K R Lee

Publications and source records attributed to K R Lee.

At least 91 records · Page 5Linked to original sources
PubMed1996

Edema from intracerebral hemorrhage: the role of thrombin.

The mechanism by which intracerebral hemorrhage leads to the formation of brain edema is unknown. This study assesses the components of blood to determine if any are toxic to surrounding brain. Various solutions were infused stereotactically into the right basal ganglia of rats. The animals were sacrificed 24 hours later; brain edema and ion contents were measured. Whole blood caused an increase in brain water content and ion changes consistent with brain edema. Concentrated blood cells, serum from clotted blood, and plasma from unclotted blood all failed to provoke edema formation when infused directly into the brain. On the other hand, activation of the coagulation cascade by adding prothrombinase to plasma did produce brain edema. The edema response to whole blood could be prevented by adding a specific thrombin inhibitor, hirudin, to the injected blood. This study indicates that thrombin plays an important role in edema formation from an intracerebral blood clot.

Animals↗
PubMed1996

Thrombin-soaked gelatin sponge and brain edema in rats.

Previous work from this laboratory has shown that injection of thrombin into rat basal ganglia causes brain edema. This study investigates the effect on rat brain of thrombin-soaked gelatin sponge (used for intraoperative hemostasis in clinical situations) at a concentration similar to that used in humans. Three models were developed to evaluate this effect. In the first model, a gelatin sponge soaked with vehicle or thrombin (100 U/cm3) was placed on the intact pia of the right frontal lobe in rats without cortical lesions. In the second model, frontal cortex was excised (3 mm3) and the exposed brain was cauterized with electrocoagulation. Gelatin sponge was soaked with vehicle or thrombin (1000, 100, 10, or 1 U/cm3) and placed in the lesion site. In the third model, hirudin, a specific thrombin antagonist, was added to the thrombin-soaked gelatin sponge and placed in a similar cortical lesion to determine if the observed effects were specific to thrombin. The dose-response range for thrombin was determined qualitatively by magnetic resonance (MR) imaging and quantitatively by brain edema formation 24 hours after exposure. We found no edema in the cortically intact rats. The rats given cortical lesions developed significant edema when subjected to 1000, 100, and 10 U/cm3 thrombin as seen on MR imaging and at 100 and 10 U/cm3 thrombin as revealed by wet/dry weight and ion studies of brain tissue. Topical hirudin prevented thrombin-induced edema. It is concluded that thrombin-soaked gelatin sponges cause or enhance significant brain edema in rats at concentrations typically used for human neurosurgery.

Administration, Topical↗
PubMed1996

Comparison of the in vivo wear rates of 43 surgically retrieved direct compression molded and ram extruded ultra high molecular weight polyethylene acetabular components.

The objective of this study was to investigate retrieved ultra high molecular weight polyethylene (UHMWPE) liners from Total HIp Arthroplasty (THA) revisions. The amount of in vivo wear on compression molded v. ram extruded and machined acetabular liners was the focus of comparison between 43 surgically retrieved samples. The principal experimental methods were scanning electron microscope (SEM) observations and a fluid displacement method to quantify volumetric wear. SEM observations revealed similar wear mechanisms between the compression molded and ram extruded and machined UHMWPE retrieved liners. More third body wear corresponded with more volumetric in vivo wear. This study found that the ram extruded and machined UHMWPE liners had a significantly larger average wear rate than the compression molded UHMWPE liners. In order to determine whether the observed difference in wear rates can be attributed to the different types of UHMWPE processing, a more controlled experiment would have to be performed.

Hip Prosthesis↗
PubMed1995

Atypical endocervical glandular cells: accuracy of cytologic diagnosis.

Atypical cells thought to be of endocervical glandular origin often cause diagnostic uncertainty in cervicovaginal smears. For this reason consecutive cases of endocervical glandular atypia diagnosed in smears were correlated with subsequent biopsy diagnoses and then retrospectively reviewed. Smears were originally diagnosed as "mild glandular atypia, probably reactive" or "severe glandular atypia, suggestive of adenocarcinoma in situ" (AIS). Biopsy follow-up was obtained on 34 of 58 patients diagnosed with severe endocervical glandular atypia. Nine patients (26%) had AIS, three with concomitant high-grade squamous intraepithelial lesions (HSIL) and tow with invasive adenocarcinoma. Eighteen patients (53%) had HSIL only. Seven had benign changes. Of 152 patients diagnosed with mild glandular atypia, biopsy follow-up was obtained on 40. One patient had AIS; 14 (35%) had HSIL; one had low-grade SIL (LSIL); and 24 (60%) had benign changes. Blinded review of these smears yielded results similar to those in the biopsy follow-up, that is, the prediction of AIS on smears included most cases of AIS, some invasive adenocarcinomas, a significant number of HSIL, cases and a few benign lesions. A review diagnosis of "reactive glandular cells" proved to be HSIL in 31% of cases and AIS in one case. We conclude that patients with a diagnosis of severe glandular atypia in smears may prove to have AIS or invasive adenocarcinoma, but often have HSIL without concomitant AIS. In addition, although "reactive" glandular atypia in smears usually reflects a benign condition, a significant minority of such patients prove to have HSIL.

Adenocarcinoma↗
PubMed1995

Carcinosarcoma (malignant mixed müllerian tumor) of the uterus with a rhabdoid tumor component. An immunohistochemical, ultrastructural, and immunoelectron microscopic case study.

A case of uterine carcinosarcoma (malignant mixed müllerian tumor) of the uterus containing a rhabdoid tumor element is described. In addition to a malignant glandular component and anaplastic sarcomatous areas, this tumor had multiple foci with histologic and ultrastructural features of malignant rhabdoid tumor. Vimentin positivity by immunohistochemistry was confirmed by immunoelectron microscopy. Although three malignant rhabdoid tumors of the uterus have been previously described, in addition to rhabdoid differentiation in an endometrial stromal sarcoma, to our knowledge this is the first report of rhabdoid tumor differentiation occurring within a uterine carcinosarcoma.

Aged↗
PubMed1995

Gonococcal abscess of the obturator internal muscle: use of new diagnostic tools may eliminate the need for surgical intervention.

Obturator internal muscle (OIM) abscess or pyomyositis, a poorly recognized intrapelvic infection, is characterized by limping, pain in the hip with limited movement, and the sciatic type of radiating leg pain. With the use of advanced diagnostic tools such as computed tomography (CT), magnetic resonance imaging, and radionuclide scans, several cases of OIM abscess have been diagnosed; these cases have recently been reported in the English-language literature. Staphylococcus aureus is the predominant organism isolated from OIM abscesses. Gonococcal abscess involving the OIM has not been reported. We describe a case of gonococcal OIM abscess in an adolescent female whose condition was successfully diagnosed and managed with the use of CT-guided needle aspiration and antibiotic therapy. We review the English-language literature regarding the use of newly developed tools in the diagnosis of OIM abscess.

Abscess↗
PubMed1995

Prophylactic antibiotic use in pediatric cardiovascular surgery: a survey of current practice.

There is little information on prophylactic antibiotic practice in pediatric cardiovascular surgery. A consensus prophylactic antibiotic practice, if identified, might serve as a standard to which alternative prophylactic antibiotic practice could be compared. We surveyed North American academic centers with pediatric cardiovascular surgery programs regarding their standard antimicrobial prophylaxis regimens, duration of prophylaxis and modification of prophylaxis for lesion, patient age or medical device considerations. Forty-three (81%) of 53 centers responded; not all responses were complete. Monotherapy was used by 39 (91%) of 43; 38 (97%) of 39 used a 1st or 2nd generation cephalosporin (cefazolin 24, cefamandole 8, cefuroxime 4, cephapirin 1, unspecified 1) and 1 of 39 used vancomycin. Only 4 (9%) of 43 used 2 antibiotics. Prophylactic antibiotics were started pre- or intraoperatively by 41 of 43 centers and discontinued within 2 days by 25 of 37. Prophylactic antibiotics were often continued while thoracostomy tubes (29 of 43), mediastinal tubes (31 of 43) or transthoracic vascular catheters (22 of 43) were in place, but usually not for endotracheal tubes (6 of 43), arterial (9 of 43) or percutaneous central venous (13 of 43) catheters or temporary pacing wires (6 of 43). Our survey indicates that the consensus prophylactic antibiotic regimen for pediatric cardiovascular surgery is monotherapy with a first or second generation cephalosporin, used for < or = 2 days or until transthoracic medical devices are removed.

Anti-Bacterial Agents↗
PubMed1995

Abdominal wall hernias: review of herniography and correlation with cross-sectional imaging.

Herniography is an accurate means of identifying groin hernias when the clinical diagnosis is uncertain. Its role in evaluation of other types of ventral hernias is less clear; however, with minor modifications in technique, herniography is also useful in these cases. This article reviews the technique of herniography, normal variations in anatomy, and interpretation of herniograms of the groin and anterior abdominal wall on the basis of 72 patients studied over 3 1/2 years. Herniography is also compared with cross-sectional imaging techniques. Inguinal and femoral hernias are best shown and classified with herniography. Ventral hernias are well demonstrated by both herniography and cross-sectional imaging; however, herniation of only fat and supine imaging may lead to misdiagnosis with computed tomography or ultrasound. Spigelian hernias are probably best depicted with cross-sectional imaging. Diagnostic pitfalls of herniography are reviewed, including the need for obtaining postexercise radiographs, oblique radiographs, and tangential radiographs.

Female↗
PubMed1995

Intracerebral infusion of thrombin as a cause of brain edema.

Purified thrombin from an exogenous source is a hemostatic agent commonly used in neurosurgical procedures. The toxicity of thrombin in the brain, however, has not been examined. This study was performed to assess the effect of thrombin on brain parenchyma, using the formation of brain edema as an indicator of injury. Ten microliters of test solution was infused stereotactically into the right basal ganglia of rats. The animals were sacrificed 24 hours later, and the extent of brain edema and ion content were measured. Concentrations of human thrombin as low as 1 U/microliter resulted in a significant increase in brain water content. Rats receiving 10 U/microliters had a mortality rate of 33% compared to no mortality in the groups receiving smaller doses. Thrombin-induced brain edema was inhibited by a specific and potent thrombin inhibitor, hirudin. A medical grade of bovine thrombin commonly used in surgery also caused brain edema when injected at a concentration of 2 U/microliters. Edema formation was prevented by another highly specific thrombin inhibitor, N alpha-(2-Naphthalenesulfonylglycyl)-4-DL-phenylalaninepiperidid e (alpha-NAPAP). Thrombin-induced brain edema was accompanied by increases in brain sodium and chloride contents and a decrease in brain potassium content. Changes in brain ions were inhibited by both hirudin and alpha-NAPAP, corresponding to the inhibition of brain water accumulation. This study shows that thrombin causes brain edema when infused into the brain at concentrations as low as 1 U/microliter, an amount within the range of concentrations used for topical hemostasis in neurosurgery.

Animals↗
PubMed1994

Functional association of essential splicing factor(s) with PRP19 in a protein complex.

We have previously shown that the yeast PRP19 protein is a spliceosomal component, but is not tightly associated with small nuclear RNAs. It appears to associate with the spliceosome concomitant with or just after dissociation of the U4 small nuclear RNA during spliceosome assembly. We have found that PRP19 is associated with a protein complex in the splicing extract and that at least one of the associated components is essential for splicing. Taking advantage of the epitope tagging technique, we have isolated the PRP19-associated complex by affinity chromatography. The isolated complex is functional for complementation for the heat-inactivated prp19 mutant extract, and consists of at least seven polypeptides in addition to PRP19. At least three of these can interact directly with the PRP19 protein. We also show that the PRP19 protein itself is in an oligomeric form, which might be a prerequisite for its interaction with these proteins.

Base Sequence↗
PubMed1994

Traditional and nontraditional histopathologic predictors of recurrence in uterine endometrioid adenocarcinoma.

Ninety-three consecutive operative cases of myometrial invasive endometrioid adenocarcinoma of the uterus without evidence of extrauterine spread at surgery were reviewed to determine whether any histopathologic features other than those traditionally reported might predict recurrence. Recurrence was associated with traditionally analyzed features of deep myometrial invasion, high FIGO grade, vascular space invasion, and cervical stromal invasion as well as patient age. In addition, a diffuse pattern of myometrial invasion was associated with an increased risk for recurrence. Contrary to results from previous studies, no increased risk was seen with high nuclear grade or the presence of perivascular lymphocytic infiltrates. When adjusted for traditional parameters, perivascular lymphocytes and a tumor-host inflammatory response were associated with prolonged time to recurrence. A desmoplastic host response or residual adenomyosis were unrelated to recurrence.

Abdominal Neoplasms↗
PubMed1994

MRI of Joubert's syndrome.

OBJECTIVE: To report five cases of the rare Joubert's syndrome. SUBJECTS: All five cases were studied by 1.0-Tesla MRI. All the patients showed typical clinical manifestations of Joubert's syndrome including neonatal respiratory abnormalities, developmental delay, ataxia, retinal atrophy and nystagmus. RESULTS: The T1WI of MRI showed characteristic MRI features of Joubert's syndrome including dilatation of the fourth ventricle with some appearing bat-wing shaped, elongation and stretching of the superior cerebellar peduncles, dysphasia of the vermis, widening of the foramen of Magendie and the posterior cistern. One case was associated with encephalomeningocele. CONCLUSIONS: MRI can provide characteristic findings of Joubert's syndrome and confirm the clinical diagnosis.

Brain↗
PubMed1994

Drug use evaluation of antibiotics in a pediatric teaching hospital.

OBJECTIVE: To determine the incidence and type of antibiotic use variances at our institution. DESIGN: Inpatient bacterial culture and susceptibility results were reviewed for 1 week per month. Medication administration records were evaluated to determine whether antibiotic selection was appropriate, given the susceptibility of the organism. Process indicators included use of the least costly antibiotic, as well as appropriate dose, interval, and route of administration. The complete medical record was reviewed for all patients if management did not appear to meet criteria. SETTING: A 225-bed, tertiary-care children's teaching hospital. RESULTS: Thirty-five (8.2%) of 428 patients reviewed over 12 months had a total of 49 variances: failure to treat (3), treatment of contaminant/colonizer (2), use of more costly agent (10), failure to revise therapy (8), inappropriate route (2), inappropriate empiric antibiotic (4), incorrect dose (3), unnecessary multiple antibiotics (6), inappropriate drug (8), and prolonged prophylaxis (3). CONCLUSIONS: Thirty-five patients with 10 types of variances were identified during the study. Follow-up monitoring will assess the impact of educational efforts on the incidence of variances. Specific problem antibiotics have been identified for further audits.

Anti-Bacterial Agents↗
PubMed1994

Staphylococcus epidermidis meningitis and an intraspinal abscess associated with a midthoracic dermal sinus tract.

Congenital neuroectodermal defects are associated with meningitis that is unresponsive to conventional antibiotic therapy, recurrent bacterial meningitis, or meningitis due to an organism that is not usually the cause of this disease. Midthoracic dermoid and epidermoid cysts occur rarely and are easily overlooked. We report the case of a 13-month-old boy with meningitis that was unresponsive to antimicrobial therapy. We subsequently identified an intraspinal abscess, an infection due to Staphylococcus epidermidis, and a midthoracic dermoid cyst. We emphasize the need for clinicians to have a high index of suspicion and to make a careful physical examination when antibiotic treatment fails in patients with meningitis. We also provide a detailed anatomy of a midthoracic dermoid cyst and illustrate the usefulness of magnetic resonance imaging in preoperative diagnosis of congenital neuroectodermal defects.

Abscess↗
PubMed1994

Ultrasound detection of cerebral emboli in patients with prosthetic heart valves.

This study was undertaken in 64 patients, 50 with mechanical and 14 with porcine prosthetic valves, to evaluate the incidence of intracranial emboli and their distribution in the basal cerebral arteries. The patients were studied using transcranial Doppler (EME TC2-64B, Uberlingen, Germany), with a monitoring time of two minutes over each of the internal carotid arteries, middle and anterior cerebral arteries, vertebral arteries and the basilar artery. Sixty-three of the 64 patients were stabilized on warfarin at the time of the study. The incidence of emboli signals was significantly higher in patients with mechanical compared to porcine cardiac valves (88% versus 14%, p < 0.01). The number of emboli signals was significantly higher in the anterior compared with the posterior circulation, with a median of eight signals in the internal carotid arteries (95% confidence interval 5-15), 2.5 in the vertebral arteries (95% confidence interval 1-5.5)(p < 0.03). It was also significantly higher in those patients who had undergone double (aortic and mitral) as opposed to those who had undergone single aortic valve replacement: 18 versus two signals per minute (confidence intervals 5-30.5 versus 0.5-3.5) (p < 0.01). It is concluded that subclinical emboli signals are readily detectable using transcranial Doppler and are common in patients with prosthetic heart valves. Their number depends on both the type and the number of the prosthesis, while their distribution in the basal cerebral arteries is consistent with their cardiac source.

Adult↗
PubMed1993

Yeast precursor mRNA processing protein PRP19 associates with the spliceosome concomitant with or just after dissociation of U4 small nuclear RNA.

During assembly of the spliceosome, the U4 small nuclear RNA (snRNA) interacts with the spliceosome as a preformed U4/U6-U5 triple small nuclear ribonucleoprotein (snRNP) complex. Subsequently, U4 becomes loosely associated with the spliceosome, whereas U5 and U6 remain tightly associated, suggesting unwinding of the U4/U6 duplex. We show that this step of the assembly process can be blocked by limiting the ATP concentration in the splicing reaction. We also show that the yeast precursor mRNA processing protein PRP19 becomes associated with the spliceosome during this transition. Thus, PRP19 may function in this step of spliceosome assembly.

Adenosine Triphosphate↗