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Biomedical subjects

K Ho

Publications and source records attributed to K Ho.

At least 91 records · Page 5Linked to original sources
PubMed1985

Neuropsychological and electrophysiological examination of a patient with Wilson's disease.

A patient with Wilson's disease underwent neuropsychological and electrophysiological examination 4 months following symptom onset. Although motor deficits were more severe, there was considerable impairment of cognitive and intellectual function. Auditory evoked responses were also abnormal in this patient. This case is unusual because of the early severe cognitive deficits.

Adult↗
PubMed1984

Radiosensitization by diamide at low radiation doses.

In vitro studies in this laboratory indicated that at low radiation doses (0-3 Gy), sensitization by misonidazole diminishes. We have suggested that this results from a failure of misonidazole to enhance effectively the single-hit or alpha component of cell inactivation. Our low dose assay uses a partially automated microscopic analysis procedure which scores both surviving and killed cells. If enough cells are scored, this assay provides much better accuracy at low doses than the conventional assay. Recently, we have applied our low dose assay to a study of sensitization by diamide. This was done, in part, as a test of our assay system, since many investigators have shown that diamide substantially reduces the shoulder of the hypoxic cell survival curve. At high doses (D = 6.5 to 10 Gy, S = 0.1 to 0.01) we obtained for 150 microM diamide an enhancement ratio (ER) of 2.6 for hypoxic cells and 1.1 for aerobic cells. At low doses, 0-2.5 Gy, diamide still sensitized hypoxic cells well; with 150 microM diamide, the ER at 1 Gy (S = 0.8) was 2.0, about equal to the oxygen enhancement ratio (OER) at this dose. The fact that diamide shows good sensitization at low doses with our assay adds to the credibility of the assay and reduces the likelihood that our observations with misonidazole are an artifact of our system.

Anaerobiosis↗
PubMed1984

Early renal brush border membrane adaptation to dietary phosphorus.

The present study evaluated uptake of phosphate by brush border membrane vesicles (BBMV) and alkaline phosphatase activities in brush border membrane fractions in rats fed a normal (0.6%) or low (0.03%) phosphorus diet for 24 h. After 2 min of incubation, the phosphate uptake by BBMV from rats ingesting normal and low phosphorus diets was 1,531 +/- 98 and 2,112 +/- 183 pmol/mg protein, respectively (p less than 0.025); peak glucose uptake was 226 +/- 17 and 209 +/- 42 pmol/mg protein, respectively. Vmax increased 74% in the 0.03% dietary phosphorus groups (p less than 0.005) while Km was similar between groups. Alkaline phosphatase activities were 824 +/- 48 and 816 +/- 56 nmol/min/mg protein with the respective diets. The earliest detectable increase in phosphate uptake by BBMV occurred within 4 h of dietary phosphorus deprivation while alkaline phosphatase increased 3 days later. Renal adaptation to phosphate deprivation can occur within 4 h, is not due solely to a change in the filtered load of phosphate and occurs before increases in the specific activity of alkaline phosphatase.

Adaptation, Physiological↗
PubMed1983

Effect of metabolic acidosis on phosphate transport by the renal brush-border membrane.

Metabolic acidosis produces a phosphaturia which is independent of parathyroid hormone or dietary phosphorus intake. To study the underlying mechanism, inorganic phosphate (Pi) and glucose transport were studied in brush-border membrane vesicles prepared from the renal cortex of parathyroidectomized rats gavaged for three days with either 7.5 ml of 1.6% NaCl (control) or 1.5% NH4Cl (acidosis). At killing, blood pH and plasma bicarbonate were 7.36 +/- 0.01 and 21.8 +/- 0.8 mequiv./l, respectively, in control and 7.12 +/- 0.03 (P less than 0.01) and 11.1 +/- 1.2 (P less than 0.01) in acidotic rats. Serum Pi was similar in both groups, while 24 h urine Pi excretion was higher in the acidotic group (P less than 0.01). Peak sodium-dependent uptake of Pi, measured after 1.5 min of incubation, was higher in controls than acidotic rats (4442 +/- 464 vs. 2412 +/- 259 pmol/mg protein, P less than 0.01), whereas peak glucose uptake at 1.5 min was not significantly different between the groups. Equilibrium values for Pi and glucose uptake were similar in the two groups. Km for Pi uptake in the control and acidotic animals were not different, 0.036 and 0.040 mM, respectively. By contrast, Vmax was higher in controls than in the acidotic group, 3.13 vs. 1.15 nmol/mg protein per 15 s. These results suggest that metabolic acidosis directly inhibits Pi uptake by the brush border of the proximal tubule by decreasing the availability of Pi carriers of the renal brush-border membrane.

Acidosis↗
PubMed1982

Spinal cord swelling and candidiasis. A case report.

Fusiform swelling of the spinal cord was noted myelographically in a patient with Hodgkin's disease. Autopsy revealed that the swelling was caused by Candida infection of the spinal cord. It is suggested that fungal infection be included in the differential diagnosis of spinal cord swelling in the immunosuppressed cancer patient.

Adult↗
PubMed1982

Regulation of macrophage populations. V. Evaluation of the control of macrophage Ia expression in vitro.

In response to a lymphokine (LK) produced by activated T cells, macrophages can be induced to express Ia in vitro. This appears to be a complex process comprised of a number of discernible events. Peritoneal macrophages elicited by different means, and unstimulated macrophage and monocyte populations, each had a distinct kinetic profile of Ia induction. This response was characterized most noticeably by a latent period before actual Ia expression. The latent period varied from 3 to 7 days, depending on the target population, and was correlated with the state of activation of the macrophage as reflected by 5' nucleotidase activity. In spite of the protracted time course for Ia expression, all macrophage populations could be "triggered" (committed to a subsequent program of Ia expression) by exposure to the LK for as little as 2 hr. To be triggered, however, macrophages first had to go through a period of culture as adherent cells. Both the spontaneous loss and LK-dependent acquisition of Ia correlated with the functional capacity of these macrophages as antigen-presenting cells, indicating that these events are functionally significant.

Animals↗
PubMed1981

Buoyant density and hybridization analysis of human DNA sequences, including three satellite DNAs.

Total human DNA was fractionated from the three types of Cs2SO4 gradient used to prepare satellites I, II and III. Three satellite DNAs were found: satellite I with a mean buoyant density of 1.6888 g/ml comprising about 1.3% of the total, satellite II with a mean buoyant of 1.696 g/ml, comprising about 1% of the total an satellite III with a mean buoyant density of 1.699 g/ml comprising about 2.2% of the total. The buoyant densities of these satellites after purification were 1.686, 1.694 and 1.697 m/gl, respectively. A preparation with the attributes of satellite IV was isolated from the shoulder region of a satellite III preparative gradient. In situ hybridization using complementary RNA showed that the three satellites were located predominantly on chromosomes 9, Y, 15 and 1. Satellite II also showed marked hybridization to chromosome 16. Satellites I and II and III cross-hybridized to each other but satellites I and II did not. On the basis of our hybridization data, we suggest that some of the same sequences which comprise satellite III also comprise satellite I an II.

Animals↗
PubMed1981

Inhibition of suppressor T cells in pokeweed mitogen-stimulated cultures of T and B cells by levamisole in vitro and in vivo.

The action of levamisole on immunoglobulin production was investigated in pokeweed mitogen-stimulated cultures of B and T cells. Immunoglobulin production was measured by nephelometric methods using specific antisera to IgA, IgG and IgM. Levamisole was shown to have no effect on B lymphocytes but pretreatment of T lymphocytes with levamisole resulted in an increase in immunoglobulin production which was maximal at 10(-6) M. The latter increase appeared to be due to an effect on suppressor T cells in that pretreatment of T cells depleted of suppressor cells (by irradiation or removal of T cells with receptors with IgG) did not result in an increase in immunoglobulin production. Similar effects of levamisole were demonstrated against suppressor cells induced by concanavalin A in vitro and against spontaneous suppressor cell activity in vivo. The effect of levamisole and irradiation on suppressor cell activity against particular classes of immunoglobulin varied between individuals. Suppressor cell activity against IgA production alone was demonstrated in six of 17 subjects whereas in the remainder, immunoglobulin classes. The implications of this action of levamisole for its effects in vivo are unknown, but the results appear consistent with many of the observed effects of the drug. Selection of patients with diseases associated with high suppressor cell activity may lead to more effective use of the drug.

Adult↗
PubMed1980

Progressive multifocal leukoencephalopathy and malignant lymphoma of the brain in a patient with immunosuppressive therapy.

Progressive multifocal leukoencephalopathy and malignant lymphoma of the brain were noted at postmortem examination in a 68-year-old white woman who was treated with immunosuppressive agents after renal transplantation. The two diseases are not uncommon in patients with immunodeficiency, but their occurrence in the same patient is extremely rare. This association suggests the oncogenicity of papova viruses in man. However, no papovavirus was demonstrated in the tumor by electron microscopy and immunohistochemical staining. The immunohistochemical staining of routine histology sections for the common antigen of polyomaviruses by the peroxidase anti-peroxidase technique is shown to be simple and specific for the detection of polyomaviruses in the demyelinated areas of progressive multifocal leukoencephalopathy.

Aged↗
PubMed1978

Kinetics of carbon monoxide binding to singly reduced human methemoglobin.

The kinetics of reaction of singly reduced methemoglobin (HbFe3(3+)Fe2+) with carbon monoxide have been investigated by the pulse radiolysis method. The rate constant for carbon monoxide binding to this form of hemoglobin is 4.1 X 10(6) M-1 S-1 at 24 degrees in our solutions. This value compares with existing values for various forms of hemoglobin ranging from 4 X 10(6) to 6.5 X 10(6) M-1 S-1. Addition of inositol hexaphosphate to the solutions results in a lower rate constant for carbon monoxide binding amounting to 1.1 X 10(5) M-1 S-1.

Carbon Monoxide↗
PubMedDate not supplied

Smoking, smoking cessation, and understanding of the role of multiple cardiac risk factors among the urban poor.

OBJECTIVE: To determine in a population of low socioeconomic status (SES) patients: (a) rates of current smoking and smoking cessation, (b) persons' understanding of the adverse health impact of multiple cardiovascular disease (CVD) risk factors, and (c) if the diagnosis of other CVD risk factors, specifically hypertension or hypercholesterolemia, was related to smoking cessation. DESIGN: Cross-sectional interview survey. SETTING: Community clinics and eligibility centers of the Harris County Hospital District (HD), which provides primary care to over 166,000 indigent persons in Houston, Texas. SUBJECTS: Randomly selected adults attending an HD setting for eligibility screening or primary care. RESULTS: Over 93% of subjects approached participated (n = 547). Their mean age was 40.7 years, 55% were female, and 39% had > 9 years of education. The ethnic distribution was 54% Hispanic, 28% black, and 14% non-Hispanic white. Current smoking ranged from 10% among Hispanic females to 56% among black males. The percentage of ever smokers who had quit was 24% among black males, 44% among black females, 43% among Hispanic males, and 70% among Hispanic females. The majority recognized the increase in danger from smoking in the presence of hypertension or hypercholesterolemia. Among patients who were smokers when they found out they had hypertension (n = 70), 65% reported it increased their desire to quit. After adjustment for other variables including age and known CVD, predictors of being an ex-smoker were being female (OR 2.1, 95% CI 1.3-3.5), being Hispanic (OR 2.8 95% CI 1.5-5.7), and having hypertension (OR 2.3, 95% CI 1.3-4.2). CONCLUSION: In this low SES population, there was substantial smoking cessation, widespread acknowledgment of the cumulative effect of smoking and other CVD risk factors, and some evidence that smoking cessation increased after the diagnosis of hypertension.

Adult↗
PubMedDate not supplied

Acute mesenteric ischemia in a middle-aged patient: case report and discussion.

Mesenteric ischemia usually occurs in elderly patients, especially those with predisposing factors. It has also been described in young patients using oral contraceptive pills or illicit drugs. We present a case of a middle-aged woman who developed acute focal ischemia of the small intestine without predisposing factors. The unusual presentation of this patient, combined with her relative youth, obscured the diagnosis, which was ultimately made at laparotomy. The diagnosis of mesenteric ischemia should be considered in patients of any age presenting with recurrent or severe abdominal pain, particularly when no alternative cause is apparent. The definitive study to diagnose mesenteric ischemia is angiography. Unless identified early in its course, the condition may progress to frank infarction with a significant increase in morbidity and mortality. Because of this, an aggressive approach to the diagnosis and therapy of mesenteric ischemia is essential.

Abdominal Pain↗
PubMedDate not supplied

Occult ankle fracture detected by an ankle effusion on plain radiography: a case report.

Subtle ankle fractures may escape detection on plain radiography. These occult fractures can cause prolonged disability and pain. We present a case of blunt ankle trauma where plain radiography failed to reveal any bony abnormalities. The recognition of an ankle effusion on plain radiographs prompted us to perform a computed tomography (CT) scan of the ankle. The CT scan demonstrated an anterior plafond fracture of the distal tibia, which required surgical fixation. Had the fracture not been identified, our patient would have been treated inappropriately for a ligament sprain. An occult fracture should be suspected if an ankle is grossly swollen after blunt trauma, and plain radiography demonstrates an effusion. In this circumstance, performance of further imaging studies, such as conventional or CT, are advised to rule out an occult ankle fracture.

Adult↗