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Biomedical subjects

P Chu

Publications and source records attributed to P Chu.

At least 73 records · Page 4Linked to original sources
PubMed1995

An assessment of the Coulter VCS automated differential counter scatterplots in the recognition of specific acute leukaemia variants.

The Coulter VCS is an automated differential counter, which derives a five-part differential count on the basis of differences in cell volume, high frequency conductivity and light scatter. A printed scatterplot relating volume and scatter is readily obtained. Other instruments which use automated cytochemistry can distinguish between AML and ALL, and between AML variants. It was our impression that the Coulter VCS might also be capable of such distinction on the basis of the scatterplot patterns. We therefore collected scatterplots produced by Coulter VCS analysis of peripheral blood from 63 patients presenting with acute leukaemia. The scatterplots were inspected and six basic patterns identified. The scatterplots were inspected and six basic patterns identified. The scatterplots could be reproducibly sorted into pattern-specific groups without knowledge of the diagnosis. Precise leukaemic diagnoses were made routinely by conventional morphology, cytochemistry and immunophenotyping. A comparison was then made with the scatterplot patterns. The 51 cases of AML produced examples of all six patterns. The nine cases of ALL produced only three patterns. These were shared with cases of AML, and two were also shared with the three cases of acute mixed lineage leukaemia. Thus, three of the six patterns were specific for AML, whereas no pattern was specific for ALL or acute mixed lineage acute leukaemia. One pattern was produced only by the three cases of AML M6, and another was produced only by five of the 25 cases of primitive (M0 and M1) AML.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

L-glutamine and L-asparagine stimulate Na+ -H+ exchange in porcine jejunal enterocytes.

L-Glutamine (Gln) is a major respiratory fuel and substrate for nucleic acid synthesis in mammalian intestinal cells. The structurally related amino acid, L-asparagine (Asn), stimulates the proliferative enzyme ornithine decarboxylase in colonocytes, an effect that is blocked by the Na+-H+ exchange inhibitor amiloride. In an epithelial cell line derived from newborn piglet jejunum (IPEC-J2 cells), we determined intracellular pH (pHi) by computer-assisted microfluorimetry in single cells loaded with pH-sensitive dye 2',7'-bis(2-carboxyethyl)5-(6)- carboxyfluorescein. Resting pHi in N-2-hydroxyethylpiperazine-N'-2- ethanesulfonic acid-buffered NaCl Ringer was 7.06 +/- 0.02. Removal of external Na+ caused reversible acidification; recovery of pHi from NH+4-induced acid load was Na+ dependent, amiloride inhibitable, and Cl-independent. Asn and Gln had no measurable effect on resting pHi, but pretreatment with Asn or Gln induced a consistent twofold increase in pHi recovery from an acid challenge that was not seen with L-proline, D-glutamine, or L-phenylalanine. Inhibition of Gln metabolism by aminooxyacetate abolished the stimulatory effect of Gln on the exchanger. The tumor promotor phorbol 12-myristate 13-acetate (PMA) stimulated recovery rate from acid load and also increased resting pHi. The effects of PMA and Gln on Na+-H+ exchange from acid load were additive. Stimulation of Na+-H+ exchange by PMA, but not by Gln, was inhibited by protein kinase C (PKC) inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpeperazine. We conclude that Gln metabolism stimulates Na+-H+ exchange of acid-loaded porcine enterocytes by a mechanism not requiring activation of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Rapid correction of metabolic acidosis in chronic renal failure: effect on parathyroid hormone activity.

To investigate the effect of rapid correction of chronic metabolic acidosis on circulating intact parathyroid hormone (I-PTH) activity by free calcium clamp in chronic renal failure, 18 patients were enrolled in this study. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was clamped at the preinfusion level throughout the entire procedure. The plasma pH, bicarbonate, total CO2, sodium, serum total calcium and 1,25(OH)2 vitamin D3 levels increased significantly while serum concentrations of I-PTH, alkaline phosphatase and albumin showed significant decreases after bicarbonate infusion. The plasma ionized calcium, potassium, serum magnesium and inorganic phosphorus levels showed no significant difference before and after bicarbonate infusion. These results demonstrate that rapid correction of metabolic acidosis attenuates circulating PTH activity in chronic renal failure and may underline the importance of maintaining normal acid-base homeostasis particularly in the presence of secondary hyperparathyroidism.

Acid-Base Equilibrium↗
PubMed1994

The histopathologic spectrum of palisaded neutrophilic and granulomatous dermatitis in patients with collagen vascular disease.

BACKGROUND AND DESIGN: Patients with lupus erythematosus, rheumatoid arthritis, and other diseases in which circulating immune complexes occur can develop a papular eruption on the extremities. Terms including Churg-Strauss granuloma, cutaneous extravascular necrotizing granuloma, rheumatoid papules, superficial ulcerating rheumatoid necrobiosis, and interstitial granulomatous dermatitis with arthritis have been given to this entity. We evaluated the clinical and histopathologic features of six patients with systemic lupus erythematosus, two patients with rheumatoid arthritis, and one patient with an incompletely characterized collagen vascular disease who developed cutaneous papules. RESULTS: The lesions were located largely on the extremities and were symmetrically distributed in most of the patients. They ranged from a few to many and from skin colored to erythematous, and they had smooth, ulcerated, or umbilicated surfaces. Histopathologic examination showed a spectrum of changes that, we believe, reflect the evolution of lesions, ie, leukocytoclastic vasculitis with dense neutrophilic infiltrates and degenerated collagen in early lesions; palisaded granulomas surrounding leukocytoclastic debris, fibrin, and altered collagen in fully developed lesions; and, as the process wanes, palisaded granulomas with dermal fibrosis and scant neutrophilic debris. Each stage of development elicits a different differential diagnosis, which can be resolved by the application of histopathologic criteria. CONCLUSION: The histopathologic findings are consonant with the evolution of an immune complex-mediated disease. The diverse histopathologic, and sometimes clinical, appearances account for the variety of names given to this condition. We propose the name palisaded neutrophilic and granulomatous dermatitis of immune complex disease to reflect the histopathologic evolution and clinical aspects of this condition.

Adult↗
PubMed1993

Nonimmune thyroid destruction results from transgenic overexpression of an allogeneic major histocompatibility complex class I protein.

The overexpression of major histocompatibility complex (MHC) class I molecules in endocrine epithelial cells is an early feature of autoimmune thyroid disease and insulin-dependent diabetes mellitus, which may reflect a cellular response, e.g., to viruses or toxins. Evidence from a transgenic model in pancreatic beta cells suggests that MHC class I overexpression could play an independent role in endocrine cell destruction. We demonstrate in this study that the transgenic overexpression of an allogeneic MHC class I protein (H-2Kb) linked to the rat thyroglobulin promoter, in H-2Kk mice homozygous for the transgene, leads to thyrocyte atrophy, hypothyroidism, growth retardation, and death. Thyrocyte atrophy occurred in the absence of lymphocytic infiltration. Tolerance to allogeneic class I was revealed by the reduced ability of primed lymphocytes from transgenic mice to lyse H-2Kb target cells in vitro. This nonimmune form of thyrocyte destruction and hypothyroidism recapitulates the beta-cell destruction and diabetes that results from transgenic overexpression of MHC class I molecules in pancreatic beta cells. Thus, we conclude that overexpression of MHC class I molecules may be a general mechanism that directly impairs endocrine epithelial cell viability.

Animals↗
PubMed1992

An eruptive vascular proliferation resembling acquired tufted angioma in the recipient of a liver transplant.

A 59-year-old man developed grouped erythematous papules on the skin of the right axilla and arm shortly after orthotopic liver transplantation. Histologic changes closely resembled those of acquired tufted angioma, with capillary lobules studding the dermis. The lesions spontaneously involuted over several months. Histopathologic and immunohistochemical findings excluded Kaposi's sarcoma and bacillary angiomatosis, the two vascular proliferations most frequently seen in the immunocompromised host. We believe that our case is one of acquired tufted angioma appearing as an eruptive condition similar to eruptive pyogenic granuloma, to which it seems closely related. The involution of lesions in this case is unexplained.

Arm↗
PubMed1992

Histologic features of cutaneous sinus histiocytosis (Rosai-Dorfman disease): study of cases both with and without systemic involvement.

Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) is a systemic proliferation of cells that resemble the sinus histiocytes of lymph nodes. Whereas initial reports highlighted the often striking cervical adenopathy, more than 40% of patients have extranodal involvement. Cutaneous lesions are the most common form of extranodal disease, but cases that present as cutaneous disease without lymph node involvement are rare. We examined biopsies from three patients with cutaneous lesions of sinus histiocytosis, none of whom had detectable systemic involvement, and compared them to those of two patients whose lymph nodes were involved by the disease. The histology of skin lesions in all five cases showed dense nodular or diffuse infiltrates of "histiocytes," emperipolesis of lymphocytes, neutrophils, and plasma cells. "Histiocytes" were present in lumens of dilated lymphatics. At the peripheries of the lesions were lymphoid aggregates and thick-walled vessels surrounded by plasma cells. Staining with anti-S-100 protein antibody showed marked cytoplasmic positivity in the "histiocytes" in each case. The only features that differed among the two groups were the presence of pseudoepitheliomatous hyperplasia and infiltrates of eosinophils in one case in which the disease was limited to the skin. We believe that cutaneous sinus histiocytosis can be specifically diagnosed by skin biopsy. Because cutaneous sinus histiocytosis may be unfamiliar to general pathologists, dermatopathologists, and dermatologists, cases limited to the skin may be under-recognized.

Adult↗
PubMed1992

Role of creatine phosphokinase in predicting acute renal failure in hypocalcemic exertional heat stroke.

Recruits frequently develop hypocalcemia in exertional heat stroke (ExHS) with rhabdomyolysis and acute renal failure (ARF) from intensive training. It usually indicated severe skeletal muscle damage. However, the relative risk of ARF in ExHS patients complicated with hypocalcemia was unknown. The present study was undertaken to evaluate the value of peak serum creatine phosphokinase (CPK) level in predicting ARF in ExHS patients with hypocalcemia. Sixty-eight army recruits with ExHS were hospitalized at the Tri-Service General Hospital, Taiwan: 17 with ARF and hypocalcemia (group A); 7 with ARF but without hypocalcemia (group B); 20 without ARF but with hypocalcemia (group C); and 24 without ARF or hypocalcemia (group D). In the 24 patients with ARF (groups A and B) the serum phosphate and peak CPK levels were significantly higher than in patients without ARF (groups C and D; p < 0.001), serum calcium levels were also significantly lower in the former (p < 0.001). In the 37 patients with hypocalcemia (groups A and C), the peak serum CPK levels were significantly higher than in those without hypocalcemia (groups B and D; p < 0.001). There was a higher proportion of hypocalcemic patients with peak serum CPK levels greater than 10,000 U/l among ARF compared with patients without ARF (chi 2 = 12.48, p < 0.001). In 24 patients with ARF, there was a negative correlation between serum Ca and peak CPK levels (t = 3.37, r = -0.58, p < 0.01). However, a positive correlation was found between serum creatinine and peak serum CPK levels in 37 patients with hypocalcemia (t = 2.47, r = 0.39, p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1992

Nonmelanoma skin cancers and infection with the human immunodeficiency virus.

BACKGROUND AND DESIGN: Forty-eight human immunodeficiency virus-infected patients with nonmelanoma skin cancers seen during a four-year period were evaluated in a retrospective, case-control study. Patients were followed up after therapy and recurrence rates were determined. RESULTS: One hundred and sixteen nonmelanoma skin cancers were identified, 101 of which were basal cell carcinomas (87%), mostly superficial multicentric (67%) of the trunk (62%). There were 15 low-grade squamous cell carcinomas, most commonly of the head and neck. Half of the patients had multiple cancers. Compared with age-matched controls, the patients with skin cancer more commonly had blue/hazel eyes (89% vs 66%; odds ratio [OR] 4.1; confidence interval [CI], 1.25 to 13.44; P = .033), blond hair (42% vs 13%; OR = 4.53; CI, 1.40 to 13.74, P = .003), a family history of skin cancer (45% vs 5%; OR = 11.88; CI, 2.85 to 49.57; P = .00), and a history of regular sunbathing (92% vs 48%; OR = 11.24; CI, 3.17 to 39.83; P = .00). The number of cancers or the presence of squamous cell carcinoma did not correlate with the degree of immunosuppression. The recurrence rate for basal cell carcinomas following standard treatment methods (mostly curettage and electrodesiccation and excision) was 5.4% for those tumors followed up for longer than 12 months. Three of the 15 squamous cell carcinomas recurred, all following curettage and electrodesiccation. CONCLUSION: Nonmelanoma skin cancers are a not uncommon cutaneous finding in human immunodeficiency virus-infected patients. The major risk factors for developing skin cancer in association with human immunodeficiency virus disease seem to be the same as in the normal population--fair skin, a positive family history, and sun exposure. Standard treatment methods seem to be associated with acceptable cure rates, except for squamous cell carcinomas, which had a high (20%) recurrence rate following curettage and electrodesiccation.

Adult↗
PubMed1991

Knee hyaline cartilage evaluated with MR imaging: a cadaveric study involving multiple imaging sequences and intraarticular injection of gadolinium and saline solution.

Magnetic resonance (MR) imaging of cadaveric knees was performed to determine optimal sequences for visualization of hyaline cartilage. Six fresh-frozen cadaveric knees were imaged with a 1.5-T imager by means of standard and hybrid fat suppression (HFS) spin-echo techniques, with and without intraarticular injection of saline solution and gadopentetate dimeglumine. The knees then were sectioned at 4-mm intervals. Both the real and the imaged cartilage thicknesses were measured. Areas of cartilage thinning and focal defects seen in the cadaveric sections were most accurately matched, in both the presence and the absence of intraarticular saline solution simulating joint fluid, by images obtained with the T1-weighted HFS sequences. Accurate imaging of hyaline cartilage thickness with differentiation of cartilage from fluid was possible routinely. Standard and HFS spin-echo images obtained after intraarticular injection of gadopentetate dimeglumine depicted cartilage less accurately than HFS sequences either with or without saline injection. MR imaging with T1-weighted HFS sequences provided superior visualization of cartilage, enabling accurate measurements of cartilage thickness and differentiation of cartilage from saline solution simulating joint fluid.

Cartilage, Articular↗
PubMed1991

Elderly patients with suppressed serum TSH but normal free thyroid hormone levels usually have mild thyroid overactivity and are at increased risk of developing overt hyperthyroidism.

The clinical and biochemical characteristics of 15 elderly patients with low levels of thyrotrophin (TSH) (< 0.1 mU/L) but normal free tri-iodothyronine (T3) and free thyroxine (T4) (group S) were compared with 10 euthyroid subjects (group E) and 10 hyperthyroid patients (group T). Free T3 and free T4 were significantly higher (p < 0.05) in group S (6.3 +/- 0.5 and 18.6 +/- 1.0 pmol/l, respectively) than in group E (4.6 +/- 0.3, 12.6 +/- 0.6). In common with elderly hyperthyroid patients (group T), patients in group S had few signs or symptoms of thyrotoxicosis, but the Wayne score (clinical index of hyperthyroidism) was higher in group S than in euthyroid subjects (p < 0.05). Thyroid microsomal, thyroglobulin or thyrotrophin receptor antibodies were common in group T (n = 9) but not in groups S (n = 2) or E (n = 1). This suggests a low prevalence of Graves' disease in group S compared to group T. Combined thyrotrophin releasing hormone (TRH; 200 micrograms i.v.) and gonadotrophin releasing hormone (GnRH; 100 micrograms i.v.) tests were performed; no cases of low TSH due to hypopituitarism were identified in group S. During a mean of 7.9 (4-12) months of observation TSH reverted to the normal range (> 0.2 mU/L) in 7 of 15 patients in group S; thyroid hormone concentrations rose above the normal range in four, however, only two patients required treatment for hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Identification of the 2A10 antigen of retinal pigment epithelium as a beta 1 subunit of integrin.

In previous studies the 2A10 antigen of retinal pigment epithelium (RPE) was described. It is a cell-surface monoclonal antibody-defined antigen whose properties suggest a possible role in cell adhesive interactions. This report identified the 2A10 antigen as a beta 1 subunit of the cell-surface extracellular matrix receptor protein, integrin. Comparative biochemical, immunochemical, and histochemical analyses of the 2A10 antibody and other antibodies directed against the beta 1 subunit of integrin indicate similar tissue distributions, immunoblotting patterns, tryptic digestion profiles, and coimmunoprecipitation of the 2A10 antigen and the beta 1 subunit of integrin. The 2A10 antigen/beta 1 subunit differed in molecular weight in different tissues, with the RPE demonstrating a form intermediate between neural and endoderm-derived tissues. The application of this new antibody to functional studies of the role of integrin in RPE cell-substrate adhesion is described in the accompanying paper.

Animals↗
PubMed1990

Loss of maternally acquired measles antibodies in well-nourished infants and response to measles vaccination, Peru.

Clinical, anthropometric, and serological evaluations were conducted at birth and at 3, 6, 9, and 10 months (post measles vaccination) in 34 well-nourished Peruvian infants. Seroconversion rate after measles vaccination was 94 percent. The rate of antibody loss was a direct function of birth titer; at age 9 months, all children had identical mean titers regardless of their titer at birth. Differences in maternally acquired measles antibodies at birth were important only during the first six months of life.

Aging↗