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Biomedical subjects

M Lee

Publications and source records attributed to M Lee.

At least 793 records · Page 44Linked to original sources
PubMed1991

The determination of the pKa of histidine residues in proteins by Raman difference spectroscopy.

Sensitive Raman difference spectroscopy was used to monitor the protonation and deprotonation of histidine residues in apo-transferrin. We have shown previously that the behavior of small molecules and/or small molecular groups bound to proteins or other large macromolecules can be studied by Raman difference spectroscopy (Yue, K.T. et al. (1989) J. Raman Spectrosc. 20, 541-545). Using this method, we have measured the Raman difference spectra of human transferrin at different pH values with respect to pH 8.9, titrating its various histidine residues. About 12 +/- 2 of the 19 residues were titrated. The pH difference spectrum of transferrin obtained is very similar to that of histidine in solution, but with clear differences in the 1200-1400 cm-1 region. A titration curve with pKa of 6.08 +/- 0.01 fit the data of histidine in solution and a value of 6.56 +/- 0.02 was found for the average value of the 12 histidine residues inside transferrin. The technique has enough sensitivity at present to monitor a single histidine residue in a 130 kDa molecule and to determine the titration curve of one residue in a 40 kDa protein.

Apoproteins↗
PubMed1991

Reproductive factors and colorectal cancer risk among Chinese females.

We report results from a population-based case-control study of colorectal cancer among Chinese women in western North America (NA) and the People's Republic of China (China). A common protocol was used to assess reproductive characteristics and hormone use of 395 Chinese women (189 from NA and 206 from China) with cancer of the colon or rectum and of 1112 age-matched Chinese controls (494 from NA and 618 from China). In NA, risks for cancers of both the colon and rectum were lower among parous compared to nulliparous women (odds ratio for colorectal cancer, 0.6, P = 0.08), but the trend in risk was not smooth with increasing number of livebirths. This association with parity was absent for both cancer sites in China. There were no consistent patterns in the relationships between other reproductive factors (including age at menarche, age at first livebirth, menopausal status) and risk of colon and rectal cancer on either continent.

Adult↗
PubMed1991

A solid phase enzyme immunoassay for serum amyloid A (SAA) protein. Clinical evaluation.

An enzyme-linked immunosorbent assay for serum amyloid A protein using commercially available antisera has been developed. Immulon II microtitre plates are coated with undenatured sera by overnight incubation at 4 degrees C. The assay combines the advantages of simplicity, rapidity, precision, sensitivity and safety and confirms the suitability of measuring serum amyloid A protein as a sensitive marker during the acute-phase response. This method permits the rapid processing of a large number of samples.

Adult↗
PubMed1991

The role of hematogenous and intrinsic precursor cells in lymphocyte production in murine bone marrow and thymus.

It is well recognized that the bone marrow contains cells that can repopulate a depleted thymus as well as cells that can be induced to express phenotypic markers characteristic of T cells. It is not known, however, to what extent thymocytopoiesis in the normal thymus relies on immigrant, bone marrow-derived cells, nor whether some T cell precursors have entered the bone marrow from the circulation. We used the parabiotic system to test whether thymocytopoiesis relies on progenitors intrinsic to the thymus or on cells that enter the organ from the circulation. In the same system, we have also investigated whether Thy-1- bone marrow lymphocytes that respond to phytohemagglutinin (PHA) by proliferation and Thy-1 expression are produced by myelogenous or hematogenous progenitors. Syngeneic CBA/HT6 and CBA/CaJ mice were joined in parabiotic union at 4-6 weeks of age. Cross circulation between the two partners was verified by the equilibration of Evans' blue dye injected into one partner and by the equilibration of PHA-responsive T cells in the spleen of the parabionts. Chromosome spreads were prepared from the PHA-stimulated T cell-depleted bone marrow and from spontaneously proliferating thymocytes as well as from thymocytes stimulated by PHA or Concanavalin A (Con A). The exchange of spleen colony-forming units (CFU-S) in the femoral marrow was assessed by karyotyping individual spleen colonies. Regardless of the length of parabiotic union, ranging from 4 to 20 weeks, Thy-1-, PHA-responsive bond marrow lymphocytes remained predominantly of the host type with only 3% being derived from the opposite partner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Evaluation of the protective effect of verapamil on reperfusion injury by 111In anticardiac myosin antibody in canine myocardial infarction.

We quantitated the protective effect of verapamil on reperfusion injury in canine myocardial infarct using 111In-anticardiac myosin antibody and correlated to the electronmicroscopic findings. Experimental myocardial infarction was performed by one hour occlusion of the anterior descending coronary artery and followed by reperfusion. Saline or verapamil (0.6 mg/kg/hr) was started at 40 minutes after coronary artery occlusion and continued throughout the experiment. There was an inverse exponential relationship between anticardiac myosin uptake and regional coronary blood flow in both the control (r = -0.86) and the verapamil treated (r = -0.71) groups. Less uptake of 111In-anticardiac myosin antibody was observed in the verapamil treated group than in the control group of the regions where blood flow was lower than 30% of normal. In the control group, the myocardium showed signs of the typical contraction band necrosis. In the verapamil treated group, however, the myocardium contained fewer electron dense granules and mild degree of contraction bands.

Animals↗
PubMed1991

Apraclonidine prophylaxis for postcycloplegic intraocular pressure spikes.

A randomized, prospective, double-masked study was undertaken to determine the risk of postcycloplegic intraocular pressure spikes in patients with open-angle glaucoma and to evaluate apraclonidine prophylaxis in minimizing these spikes. Patients were stratified as miotic treated or untreated and each group was randomized to receive either placebo (artificial tears) or apraclonidine in both eyes before instillation of tropicamide. In both the miotic treated and untreated groups that received placebo, there was a high incidence, (37% and 38%, respectively) of clinically significant (greater than or equal to 6 mmHg) intraocular pressure spikes after instillation of tropicamide. In both the miotic treated and untreated groups, there was a statistically significant difference in postcycloplegic intraocular pressure between the subgroup that received placebo and the group that received apraclonidine prophylaxis (P = 0.003 and P = 0.006, respectively). Additionally, four eyes that received placebo had a spike of over 10 mmHg (range, 12 to 27 mmHg), while only one eye had an increase of greater than 10 mmHg (12 mmHg) in the apraclonidine group. Thus, apraclonidine appears to be a useful agent for minimizing precipitous increases in intraocular pressure after cycloplegia in eyes of open-angle glaucoma patients prone to this complication of cycloplegia.

Adrenergic alpha-Agonists↗
PubMed1991

Cellular dimensions affecting the nucleocytoplasmic volume ratio.

Although it has long been appreciated that larger eukaryotic cells have larger nuclei, little is known about how this size relationship is maintained. Here we describe a method for measuring the aqueous volume ratio of nucleus to cytoplasm, two compartments which are interconnected via the pores in the nuclear envelope. We then use that method to identify proportional cellular dimensions in variously treated cells and in different cell types. Cells were scrape loaded with a mixture of fluorescent dextrans: Texas red dextran, average mol wt = 10,000 (TRDx10), and fluorescein isothiocyanate dextran, average mol wt = 70,000 (FDx70). After introduction into the cytoplasmic space, the TRDx10 distributed into both the nucleus and cytoplasm, whereas the FDx70 was restricted to cytoplasm, due to size exclusion by the nuclear pores. The aqueous nucleocytoplasmic volume ratio (RN/C) was determined by measuring, from fluorescence images of spread cells, total cellular fluorescence of each of the two probes and the fluorescence ratio of those probes in the cytoplasm. RN/C was unaffected by the measurement procedure or by varying temperatures between 23 degrees and 37 degrees C. Loading excess unlabeled dextrans had little effect on RN/C, with the single exception that high concentrations of large dextrans could lower RN/C in endothelial cells. Expanding intracellular membranous compartments of macrophages by phagocytosis of latex beads decreased RN/C. Expanding the same compartment by pinocytosis of sucrose, which nearly doubled total cell volume, had little effect on RN/C, indicating that nuclear volume was more closely linked to the cytoplasmic volume, exclusive of vesicular organelles, than to total cell volume. RN/C was the same in mononucleate and binucleate endothelial cells. Finally, measurements of RN/C in murine bone marrow-derived macrophages, bovine aortic endothelial cells, Swiss 3T3 fibroblasts, PtK2 cells, and CV-1 cells revealed that nuclear volume scaled allometrically with cell volume. The allometric relationship indicated that cell volume was proportional to nuclear surface area.

Animals↗
PubMed1991

Phase I-II evaluation of intravesical novantrone (mitoxantrone) in superficial bladder cancer.

The objective of this study was to determine the safety and efficacy of intravesical novantrone in refractory superficial bladder cancer. The eligibility criteria included proven carcinoma in situ or superficial transitional cell carcinoma of the bladder at stage Ta or T1 that was proven refractory to or in relapse after the use of at least one other standard anti-cancer agent. The patient was to have received no prior radiotherapy or intravesical therapy for at least 4 weeks prior to entry. Patients also did not suffer significant cardiac dysfunction, such as angina, congestive heart failure, or uncompensated cardiomyopathy. All patients were given 4-6 doses of intravesical novantrone at the same dose level at weekly dosing interval. Patients were required to retain the drugs in the bladder for 2 h. Baseline study included history/physical, hematology, blood chemistry, cystoscopy, bladder barbotage, urine cytology, cystometrogram to assess the bladder capacity, and finally, chest X-ray, EKG, and MUGA scan, if indicated. Weekly assessment involved toxicity notation, blood chemistry, hematology and urinalysis. Monthly assessment included physical examination, toxicity notation, hematology, urinalysis and blood chemistry. Within 4 weeks of completion of the last dose, patients underwent repeat cystoscopy to assess disease status. Patients who responded to the 4-6 week induction phase were entered in a monthly dose regimen for up to 5 months. A total of 23 patients were enrolled: 22 males and 1 female. One patient dropped out before receiving medication because of a protocol violation for entry criteria. Twenty-two patients were eligible for assessment of safety and 20 were eligible for assessment of efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Prospective multicenter study on isolation of human immunodeficiency virus type 1 from homosexual men after seroconversion.

A prospective multicenter study was undertaken to isolate human immunodeficiency virus type 1 (HIV-1) from 45 homosexual men for a period of 30 months after seroconversion. Efficiency of HIV-1 isolation from peripheral blood mononuclear cells was relatively stable over time, ranging from 64% at the time of seroconversion to more than 82% after 18 months of seroconversion. However, Kaplan-Meier analysis of HIV-1 culture data indicates that the cumulative proportion of HIV-1 culture positivity at 3, 6, 12, and 18 months after seroconversion was 62, 65, 84, and 92%, respectively. No significant correlation was observed between the presence of HIV-1 p24 antigen in serum, or numbers of CD4+ and CD8+ blood lymphocytes, and HIV-1 isolation within this period of time. These data suggest that HIV-1 viremia in homosexual men gradually increases to almost 100% culture positivity by 18 months after seroconversion.

HIV Seropositivity↗
PubMed1991

Squamous cell carcinoma complicating chronic osteomyelitis in a toe: a case report and review of the literature.

Squamous cell carcinoma arising from chronic osteomyelitis is uncommon. Although the majority of cases occur in the lower extremity, incidence in the foot is relatively rare, and in the toe, exceptional. This report illustrates a particularly unusual incidence of squamous cell carcinoma complicating chronic osteomyelitis of the hallux. Guidelines for early diagnosis, recommendations for treatment, and prognostic data are included.

Bone Neoplasms↗
PubMed1991

Hypogammaglobulinaemia in low grade B cell tumours; significance and therapy.

Bacterial infection is an important cause of morbidity and mortality in patients with B-cell tumors; this is related to their secondary hypogammaglobulinaemia. Two studies of intravenous replacement therapy [IVIg] have been performed in such patients: a crossover study over two years and a randomised, multicentre study over one year. Both involved infusions of IVIg [400 mg/Kg] or an equivalent volume of saline every three weeks for one year. In both studies, serious bacterial infections were considerably reduced by IVIg. Viral and fungal infections were uncommon. In the crossover study bacterial infections were more frequent in periods in which patients serum IgG levels were below the normal range [less than 6.4 g/l]. The sites of bacterial infection were similar in these studies to those in previously published reports, namely respiratory tract, skin, urinary tract and blood. There were a few mild adverse reactions which were related to the rate of infusion, but no serious toxic effects. Haematological parameters were not significantly changed by IVIg at this dose and disease progression did not appear to be changed.

Agammaglobulinemia↗
PubMed1991

Studies of fluids simulating blood-like rheological properties and applications in models of arterial branches.

We studied several non-Newtonian fluids to determine how closely they simulate the flow behavior of human blood. The viscous and viscoelastic properties of these fluids were compared with human blood samples in steady flow and transient flow Couette viscometers and in an oscillatory tube flow viscoelasticity analyzer. We examined: 1) A polyacrylamide suspension (Separan AP30 and AP45) to which we added 4% isopropanol and 0.01% magnesium chloride. 2) A suspension of 2% Dextran with 16% by weight biconcave disc-shaped particles simulating red blood cells. 3) 40% ghost cells prepared according to Dodge in Tri (hydroxymethyl) aminomethane. These ghost cells were used to simulate the two-phase flow behavior of blood. 4) A suspension of 5% Dextran (70,000) with 12% polystyrene particles (diameter of 1 micron) and 10 mMol calcium chloride. All these fluids closely approximate the flow behavior of blood and can be used in a variety of different experimental situations. To measure velocity distribution using a laser-Doppler-anemometer, we used fluids #1 and #3 in a rigid T-junction simulating the first septal branch of the left descending coronary artery. The measurements were done in steady and pulsatile flow experiments at different flow rate ratios. The fluids showed large differences in velocity profiles compared to Newtonian fluids.

Arteries↗
PubMed1991

[The meaning of pain in labor].

From of old, labor has been accompanied by pain and much effort has been made to eliminate or diminish the amounts of pain during labor. Little concern has yet been given to the subjective meaning of pain in labor. Recently, rates of cesarean section in Korea and in some other nations have increased rapidly and some investigators are reporting negative reactions such as anger, disappointment and feeling of loss due to lack of control over labor and its pain. These findings are thought to suggest that control of labor and its pain gives some meaning to the laboring woman. Thus the investigators sought to discover the meaning of pain during labor for Korean women. Specific objectives of this study were to explore the meaning of pain in labor to the mothers, their reactions to the experience of labor and their preference for delivery method. The subjects of this study were 95 mothers who delivered their babies in hospital from September 1989 to May 1990: 45 gave birth by vaginal delivery, and 50 by cesarean section. Data were gathered through direct interviews by the investigators, and questions were focused on five areas i.e. mothers' feelings about delivery and their babies, their feelings about of having more children, the most difficult aspect about this labor and delivery, and what they thought the differences were between vaginal delivery and cesarean section. After interview, mothers' answers were summarized, and classified according to the degree of positive or negative attitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Cesarean Section↗
PubMed1991

Significance of circumsporozoite-specific antibody in the natural transmission of Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae in an aboriginal (Orang Asli) population of central peninsula Malaysia.

Two hundred and seventy-five Orang Asli volunteers living in nine villages in the Pos Legap Valley of Perak State, peninsular Malaysia, participated in a prospective study designed to characterize the epidemiological, parasitological, and entomological characteristics of Plasmodium falciparum, P. vivax, and P. malariae malaria transmission. Prevalence rates for the three plasmodial species at initiation of the study ranged from 56% in the 0-4-year-old age group to 0% in individuals over the age of 40. Entomological surveys were conducted, enabling us to determine mosquito salivary gland-positive rates and entomological inoculation rates of 1.2 infectious mosquito bites per person per month for P. falciparum, 2.4 for P. vivax, and 0.3 for P. malariae. Cumulative incidence rates over the 16 weeks of the study, following radical cure of all volunteers, were 22.5% for P. falciparum, 12.7% for P. vivax, and 1.5% for P. malariae. The median baseline antibody titer against the immunodominant repetitive B cell epitope of P. falciparum or P. vivax circumsporozoite protein was significantly higher for volunteers who did not become parasitemic. Volunteers were selected for further study if they had evidence of being challenged with P. falciparum sporozoites during the study, based on a two-fold or greater increase in antibody titer against the immunodominant repetitive B cell epitope of the circumsporozoite protein. Resistance to infection was seen in six of 10 individuals who had high (greater than 25 OD units) baseline ELISA titers, compared with only three of 24 individuals who had low baseline ELISA titers (chi 2 P less than 0.02). A similar analysis for P. vivax did not show a significant correlation.

Adolescent↗
PubMed1991

[Toxic reduction and superior therapeutic effects on peritoneal carcinomatosis of etoposide particles suspended in oil in mice].

Two dosage forms of etoposide diluted by saline solution (Etp-sol) and etoposide particles suspended in oil (Etp-oil) were examined for the toxicity and therapeutic effects when injected intraperitoneally (ip) in mice. The 50% lethal dose (LD50) values for two weeks observation were 135 mg/kg in Etp-oil and 108 mg/kg in Etp-sol. Two days after intraperitoneal transplantation of 10(6) cells/mouse of P388 leukemia to CDF1 male mice, etoposide was injected intraperitoneally in the form of Etp-oil or Etp-sol. In the mice receiving 20mg/kg of etoposide, 11 of 19 mice given Etp-oil and 3 of 20 given Etp-sol survived to day 60. In the mice receiving 80 mg/kg of etoposide, 1 in 20 treated with Etp-oil and 8 of 20 treated with Etp-sol died from by the toxicity.

Animals↗
PubMed1991

[Electrolyte abnormality and renal insufficiency in malignant lymphoma; clinical and pathological analysis in 123 cases].

The clinical studies about the electrolyte abnormality (EA) in patients with malignant lymphoma (ML) are rarely reported. We analyzed the EA and renal insufficiency in 123 patients with ML between June. 1976 and Jan. 1989; 8 patients with Hodgkin's disease, and 115 patients with non-Hodgkin's lymphoma (NHL). Before treatment, the incidence of the EA was 24.2% and hypercalcemia, hypocalcemia, and hyperkalemia were predominant. After treatment it became to 74.7% and the number of hyponatremia and hypokalemia increased. The incidence of proteinuria and renal insufficiency (serum creatinine above 1.5 mg/dl), were 7.3% and 2.4% before treatment, and became to 26.8% and 26.8% after treatment, respectively. There was a significant difference between two groups with and without the EA before treatment as for serum lactate dehydrogenase (LDH) levels (p less than 0.01), clinical stages (p less than 0.05) and the incidence of bone marrow involvement (p less than 0.01). In 34 autopsied cases, 3 cases showed massive renal involvement and about a half of cases showed various renal changes. The EA before treatment was caused by extrarenal factors, because the incidence of proteinuria and renal insufficiency were almost same to healthy controls. And renal factors play an important role on the E.A after treatment. Above results suggest that the EA before treatment indicates the progress of malignant lymphoma and the EA after treatment means not only the progress of the disease but also therapy-related renal damages.

Adult↗