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P Chu

Publications and source records attributed to P Chu.

At least 55 records · Page 3Linked to original sources
PubMed1998

Retrovirus-mediated gene transfer into human hematopoietic stem cells.

Human hematopoietic stem cells genetically modified by retroviral-mediated gene transfer may offer new treatment options for patients with genetic disease. The potential of gene-modified hematopoietic stem cells as vehicles for gene delivery was first illustrated by the demonstration that hematopoietic systems of lethally irradiated mice can be reconstituted with retroviral vector transduced syngeneic bone marrow, and that these cells can in turn provide genetically marked progeny which persist in blood and marrow over extended time periods. In contrast, hematopoietic stem cells from large animals prove difficult to transduce with retroviral vectors and are consequently less likely to function as vehicles for long-term gene therapy. Indeed, clinically relevant levels of gene transfer into large animal and human hematopoietic stem cells has not been widely achieved. The need for improved retroviral vector systems and for understanding the biology of hematopoietic stem cell gene transfer continue to fuel intense research activity. Preliminary results from human stem cell gene marking and gene therapy trials currently underway are encouraging. This contribution reviews the underlying concepts relevant to retroviral-mediated gene transfer into hematopoietic stem cells. We survey the evolution of approaches for gene transfer into hematopoietic stem cells, from murine and large animal models to the first human clinical trials. Finally, we discuss new strategies which are currently being pursued.

Animals↗
PubMed1998

Clinical manifestations and prognostic features of acute methamphetamine intoxication.

The prevalence of amphetamine abuse and the frequency of emergency department visits for amphetamine intoxication have increased dramatically worldwide. In this study, we retrospectively investigated the relationship between the prognostic features and clinical manifestations among patients admitted to the emergency department of a university hospital for acute methamphetamine intoxication during a 6-year period. Data collected included gender, age, route of abuse, time between drug exposure and arrival at the emergency department, estimated dose, signs and symptoms, laboratory values, and complications. Emergency therapy and cooling procedures were also recorded. After excluding 26 patients with multiple-drug intoxication, 18 patients (male-to-female ratio, 11:7) were include in the analysis. The mean age was 25.6 years. Thirteen patients survived and five died. Patients who died often presented with coma (80% vs 0%, p = 0.002), shock (60% vs 8%, p = 0.044), convulsions (100% vs 23%, p = 0.007), oliguria (80% vs 0%, p = 0.002), and high body temperature (41.4 +/- 0.5 degrees C vs 39.4 +/- 2.1 degrees C, p = 0.005). Furthermore, patients who died had significantly higher concentrations of blood urea nitrogen (8.7 +/- 2.1 vs 5.6 +/- 2.0 mmol/L, p = 0.01) and serum creatinine (212 +/- 71 vs 115 +/- 27 mumol/L, p = 0.033), and lower values of arterial pH (7.12 +/- 0.12 vs 7.34 +/- 0.10, p = 0.03), than those who survived. In the fatality group, the most common complication was rhabdomyolysis with acute renal failure (5 of 5); multiple organ failure resembling that from heatstroke was the leading cause of death from acute methamphetamine intoxication. In conclusion, the adverse prognostic features in patients with acute methamphetamine intoxication include coma, shock, convulsion, oliguria, and high core temperature. Acidosis, volume depletion, and ischemic renal damage were potential risk factors for development of acute renal failure in these patients.

Acute Disease↗
PubMed1997

Transport of long-chain native fatty acids across lipid bilayer membranes indicates that transbilayer flip-flop is rate limiting.

Evidence from a number of laboratories suggests that membrane proteins may meditate the transport of physiologic fatty acids (FA) across cell membranes. However, studies using lipid membranes indicate that FA are capable of spontaneous flip-flip, raising the possibility that rapid transport through the lipid phase obviates the need for a transport protein. Determining the rate-limiting steps for transport of FA across lipid membranes, therefore, is central to understanding FA transport across cell membranes. The transport of long-chain FA across lipid membranes, from the aqueous compartment on one side of the lipid bilayer to the aqueous phase on the other side, has not been measured previously. In this study, we have used the fluorescent probe ADIFAB to monitor the time course of FA movement from the outer to the inner aqueous compartments and from the lipid membrane to the outer aqueous compartment of lipid vesicles. These two measurements, together with measurements of the lipid:aqueous partition coefficients, allowed the determination of the rate constants for binding (kon), flip-flop (kff), and dissociation (koff) for the transport of long-chain natural FA across lipid vesicles. These rates were determined using large unilamellar vesicles (LUV) of approximately 1000 A diameter, prepared by extrusion and giant unilamellar vesicles (GUV), prepared by detergent dialysis, that are >/=2000 A diameter. The results of these studies for vesicles composed of egg phosphatidylcholine (EPC) and cholesterol reveal kff values that range from 3 to 15 s-1 for LUV and from 0.1 to 1.0 s-1 for GUV, depending upon temperature and FA type. For these same vesicles, dissociation rate constants range from 4 to 40 s-1 for LUV and from 0.3 to 2.5 s-1 for GUV. In all instances, the rate constant for flip-flop is smaller than koff, and because the rate of binding is greater than the rate of transport, we conclude that flip-flop is the rate-limiting step for transport. These results demonstrate that (1) kff and koff are smaller for GUV than for LUV, (2) the rate constants increase with FA type according to oleate (18:1) < palmitate (16:0) < linoleate (18:2), and (3) the barrier for flip-flop has a significant enthalpic component. Comparison of the flip-flop rates determined for GUV with values estimated from previously reported metabolic rates for cardiac myocytes, raises the possibility that flip-flop across the lipid phase alone may not be able to support metabolic requirements.

Biological Transport↗
PubMed1997

Delta and kappa opioid receptors are differentially regulated by dynamin-dependent endocytosis when activated by the same alkaloid agonist.

Many alkaloid drugs used as analgesics activate multiple opioid receptors. Mechanisms that distinguish the actions of these drugs on the regulation of individual micro, delta, and kappa receptors are not understood. We have observed that individual cloned opioid receptors differ significantly in their regulation by rapid endocytosis in the presence of alkaloid drug etorphine, a potent agonist of mu, delta, and kappa opioid receptors. Internalization of epitope-tagged delta opioid receptors from the plasma membrane is detectable within 10 min in the presence of etorphine. In contrast, kappa receptors expressed in the same cells remain in the plasma membrane and are not internalized for >/=60 min, even when cells are exposed to saturating concentrations of etorphine. The rapid internalization of delta receptors is specifically inhibited in cells expressing K44E mutant dynamin I, suggesting that type-specific internalization of opioid receptors is mediated by clathrin-coated pits. Examination of a series of chimeric mutant kappa/delta receptors indicates that at least two receptor domains, including the highly divergent carboxyl-terminal cytoplasmic tail, determine the type specificity of this endocytic mechanism. We conclude that structurally homologous opioid receptors are differentially sorted by clathrin-mediated endocytosis following activation by the same agonist ligand. These studies identify a fundamental mechanism of receptor regulation mediating type-specific effects of analgesic drugs that activate more than one type of opioid receptor.

Adenylyl Cyclases↗
PubMed1997

Structural requirement for axonal regeneration-promoting effect of polyamines in cultured rat hippocampal neurons.

We have previously found that spermine, spermidine and putrescine promote axonal regeneration following axotomy in cultured rat hippocampal neurons. In the present study, we investigated which part of the polyamine molecule is responsible for the regeneration-promoting effect. Testing the effects of several synthetic analogues revealed that the butanediamine moiety is essential for the activity and the terminal primary amines are necessary for full agonist activity. The structure-activity relationship indicates that the regeneration-promoting effects of polyamines are not associated with NMDA receptors.

Animals↗
PubMed1997

Diffuse pagetoid squamous cell carcinoma in situ of the esophagus: a case report.

BACKGROUND: In Western countries, esophageal squamous cell carcinoma is usually advanced at presentation and is rarely diagnosed in situ. The authors studied an in situ squamous cell carcinoma that occupied the entire mucosa of a 9 cm length of esophagus, causing dysphagia for solid food in a woman aged 68 years. METHODS: The esophagectomy specimen contained a circumferential region of depressed tan mucosa in the middle and lower thirds, bordered above and below by normal squamous mucosa, without ulcer, stricture, or mass. The entire lesion was submitted for histology and evaluated with immunostains for cytokeratins and markers of Paget's cells, p53 mutation, and proliferation. RESULTS: The lesion involved 45 cm2 of mucosa. Large, atypical cells with frequent mitoses occupied the basal layers of the squamous epithelium and were often separated from more superficial maturing cells by acantholysis. Pagetoid spread of tumor cells into nonneoplastic surface and gland duct epithelium was prominent. The tumor cells expressed cytokeratins of low molecular weight, p53 gene product, and proliferating cell nuclear antigen (PCNA), but lacked markers usually seen in Paget's cells in the breast or vulva. No invasion was evident. CONCLUSIONS: This extensive in situ squamous cell carcinoma of the esophagus resulted from pagetoid spread of tumor cells. These cells had a phenotype suggestive of origin from primitive epidermal stem cells and also had overexpressed p53 and PCNA, but they lacked the capacity to penetrate the basement membrane. Flat, erythematous areas of esophageal mucosa seen during endoscopy could represent early squamous cell carcinoma and should be biopsied.

Aged↗
PubMed1997

Flip-flop is slow and rate limiting for the movement of long chain anthroyloxy fatty acids across lipid vesicles.

An issue that is central to understanding cellular fatty acid (FA) metabolism is whether physiologic transport of FA across cell membranes requires protein mediation or can be satisfied by the rate of spontaneous movement through the lipid phase. For this reason, considerable effort has been devoted to determining the rate-limiting steps for transport of FA across pure lipid bilayer membranes. Previously, we found that transbilayer flip-flop was the rate-limiting step for transport of long chain anthroyloxy FA (AOFA) across lipid bilayers and that the times for long chain AOFA flip-flop were > or = 100 s, yielding rate constants for flip-flop (k(ff)) that were < or = 0.01 s(-1) [Storch, J., & Kleinfeld, A. M. (1986) Biochemistry 25, 1717-1726; Kleinfeld, A. M., & Storch, J. (1993) Biochemistry 32, 2053-2061]. In those studies, k(ff) values were inferred from the time course of AOFA transfer between lipid vesicles. Recently, Kamp et al. [Kamp, F., Zakim, D., Zhang, F., Noy, N., & Hamilton, J. A. (1995) Biochemistry 34, 11928-11937], using pyranine trapped within lipid vesicles to detect flip-flop more directly, have reported that flip-flop rates of long chain AOFA are extremely rapid (k(ff) > 10 s(-1)) and are not rate limiting for transbilayer transport. Because no defect was apparent in our previous measurements, we have extended, for AOFA, the pyranine method of Kamp et al. (1995) by using stopped-flow fluorometry to resolve flip-flop rates of both short and long chain AOFA in vesicles. In addition, we have monitored the time course of transbilayer AOFA flip-flop using carboxyfluorescein (CF) trapped within the lipid vesicles as a resonance energy transfer (RET) acceptor of AO fluorescence. The differential quenching of AOFA fluorescence in the outer and inner leaflets of the bilayer allows flip-flop to be separated from the time course of AOFA binding to the vesicles. Results obtained from both the pyranine and CF methods indicate, in agreement with our previous results, that flip-flop of the long chain AOFA is slow relative to either the binding or the rate of dissociation from the vesicle. In particular, we find that the time constant (tau) for pyranine quenching by 2-AO-palmitate (2-AOPA) was > 40 s and that k(ff) obtained from RET in CF vesicles was about 0.003 s(-1). Also, in contrast to Kamp et al. (1995) who reported that k(ff) values were independent of FA chain length or structure for the C-12 to C-18 native and the C-18 AOFA within a factor of 2, we find that the rate of pyranine quenching for the shorter chain 11-AO-undecanoic acid is more than 50-fold faster than for the longer chain AOFA. We conclude, therefore, that transbilayer transport of the AOFA is limited by the rate of flip-flop and that this rate is a sensitive function of the AOFA structure.

Arylsulfonates↗
PubMed1997

Amphotericin B lipid complex (ABLC) for the treatment of confirmed or presumed fungal infections in immunocompromised patients with hematologic malignancies.

Sixty-four adult patients (median age 43) with hematologic malignancies who were immunocompromised after allogeneic (n = 23) or autologous (n = 9) blood/marrow transplantation, or chemotherapy (n = 32) received 68 courses of amphotericin B lipid complex (ABLC, Abelcet) at the daily dose of 5 mg/kg for presumed (n = 52) or proven (n = 16) fungal infection. The major indications for ABLC were failure of previous antifungal therapy and/or renal dysfunction. Fifty-three treatment courses in 49 patients comprising 4-58 doses (median 10) were considered evaluable. Fourteen courses administered for confirmed infections resulted in nine complete and one partial responses, and four failures (71% response). Thirty-nine empiric courses resulted in 18 complete and six partial responses, and 14 failures (64% response). The overall response rate was 66%. Five of seven evaluable patients with aspergillus pneumonia responded. Response rates were comparable for chemotherapy, autograft and allograft recipients. The change in serum creatinine from the beginning to the end of therapy was -284 to +277 mumol/l (median +24). The creatinine doubled during seven evaluable courses of therapy, five of which were associated with concomitant nephrotoxic therapy. Nephrotoxicity was comparable for transplant and chemotherapy patients. Renal dysfunction necessitated discontinuation of ABLC in only four patients. These data suggest that ABLC is effective in presumed or confirmed fungal infections in immunocompromised patients after transplantation or chemotherapy.

Adolescent↗
PubMed1997

Energy metabolism in exertional heat stroke with acute renal failure.

BACKGROUND: Heat stroke is the clinical syndrome produced when the body overheats. It can develop in the army and in healthy civilian populations who physically exert themselves in a hot and humid environment during the summer, and may result in a significant number of heat-related deaths. Since strenuous exercise is one of the major exacerbating and precipitating factors, the incidence of exertional heat stroke (ExHS) is high among military personnel undergoing military training. Furthermore, acute renal failure (ARF) may occur in 25% of patients with ExHS and it can cause metabolic alterations that affect amino acid, carbohydrate, and lipid metabolism. Adequate nutritional support is essential for the treatment of ARF. The most important determinant of nutrient requirement in ARF is the degree of hypercatabolism caused by disease associated with renal function impairment. Indirect calorimetry (IDCM) is the method by which metabolic rate is estimated from measurements of oxygen consumption and carbon dioxide production. It can also provide information about the type and rate of substrate utilization in vivo (protein, carbohydrate, and fat). METHOD: The present clinical study is a comprehensive analysis of metabolic changes which includes energy expenditure (EE) and substrate utilization in 10 patients with ExHS with ARF and 10 patients with exertional heat exhaustion (ExHE) by the use of IDCM. RESULTS: Serum urea nitrogen, creatinine, peak creatine phosphokinase levels and heart rate were significantly increased in ExHS patients during ARF stage. Serum albumin levels were significantly decreased in ExHS patients with ARF. Resting energy expenditure (REE) was increased in patients with ExHS induced ARF and was not correlated with body temperature (r = 0.421). The average increase in EE during ARF stage was about 24%. The respiratory quotient in patients with ExHS induced ARF was lower than that in normal subjects and also in patients with ExHE. Urea nitrogen appearance rate increased in patients with ExHS induced ARF and in patients with ExHE without ARF. The percentage of total REE derived from fat in ExHS induced ARF and ExHE increased, while in patients with ExHS induced ARF and ExHE, the percentages of total REE derived from carbohydrate and protein were lower than those in control subjects. CONCLUSIONS: The present results suggest that patients with exertional heat injury (both ExHS and ExHE) have hypermetabolism during the acute stage. Furthermore, patients with exertional heat-induced rhabdomyolysis and ARF have a moderately higher hypermetabolism than those without ARF during the acute stage. We believe that this mainly reflects a more pronounced reduction of the vital cell mass (muscle) in relation to body weight, and/or a compromised substrate oxidation in ExHS with ARF. Whether or not this subgroup of patients will require a higher energy/caloric support merits further investigation.

Acute Kidney Injury↗
PubMed1997

Carcinoma of the esophagus and esophagogastric junction: sensitivity of radiographic diagnosis.

OBJECTIVE: The purpose of this study was to determine the sensitivity of barium studies in revealing carcinoma of the esophagus and esophagogastric junction. MATERIALS AND METHODS: We retrospectively reviewed 50 cases of squamous cell carcinoma of the esophagus (n = 25) and adenocarcinoma of the esophagus (n = 14) or esophagogastric junction (n = 11) in which double-contrast (n = 46) or single-contrast (n = 4) barium studies had been done. The original radiology reports were reviewed to determine whether the lesions had been seen on barium studies and whether cancer had been diagnosed. Records were also reviewed to determine the number of patients who underwent esophageal endoscopy because of findings suggestive of cancer on barium studies at some point from January 1992 through December 1992. Pathology records were then reviewed to determine the number of true- and false-positive barium studies during this same period. RESULTS: Lesions were shown on barium studies in 49 (98%) of 50 patients, and carcinoma of the esophagus or esophagogastric junction was diagnosed or suspected in 48 patients (96%). In a separate part of the study, we found that endoscopy had been recommended to rule out malignant tumor in only 26 (1%) of 2484 patients who underwent barium studies at some point from January 1992 through December 1992. Endoscopy revealed cancer in 11 of those 26 patients; the remaining 15 were assumed to have false-positive radiologic examinations. Barium studies therefore had a positive predictive value of 42%. CONCLUSION: The double-contrast barium study is a sensitive technique for the diagnosis of carcinoma of the esophagus and esophagogastric junction. This high sensitivity can be achieved while recommending endoscopy in only about 1% of all patients who undergo barium studies.

Adenocarcinoma↗
PubMed1996

Preclinical assessment of human hematopoietic progenitor cell transduction in long-term marrow cultures.

Long-term marrow cultures (LTMCs) were established from 27 human marrows. Hematopoietic cells were subjected to multiple rounds of exposure to retroviral vectors during 3 weeks of culture. Seven different retroviral vectors were evaluated. LTMCs were assessed for viability, replication-competent retrovirus, progenitors capable of proliferating in immune-deficient mice, and gene transfer. The average number of adherent cells and committed granulocyte-macrophage progenitors (CFU-GM) recovered from LTMCs was 28% and 11% of the input totals, respectively. There was no evidence by marker rescue assay or polymerase chain reaction (PCR) of replication-competent virus production during LTMC. No toxicity to cellular proliferation due to the transduction procedure was observed. The adherent layers of LTMCs exposed to retroviral vectors were positive for proviral DNA by PCR and by Southern blot analysis. Fifty-three percent of 1,427 individual CFU-GM from transduced LTMC adherent layers were positive for vector-derived DNA. For neocontaining vectors, the average G418 resistance was 28% of 1,393 LTMC-derived CFU-GM. Forty percent of 187 tissues from 30 immune-deficient mice injected with human LTMC cells were positive for human DNA 4-5 weeks after adoptive transfer. These studies indicate that multiple exposures of human LTMCs to retroviral vectors result in consistent and reproducible LTMC viability and gene transfer into committed progenitors. Our results further support the use of transduced LTMC cells in clinical trials of hematopoietic stem cell gene transfer.

Animals↗
PubMed1996

Angiotropic large cell lymphoma presenting as primary adrenal insufficiency.

Angiotropic large cell lymphoma is reported in two patients who developed severe metabolic acidosis and unexplained hypotension before death. In addition to the usual multiorgan involvement of the disease, the adrenal glands of both patients were symmetrically enlarged. Histologically, the cortical vessels were engorged and filled with neoplastic lymphoid cells of B-cell lineage, whereas the parenchymal cells were compressed and atrophic. Angiotrophic large cell lymphoma seems to be a distinct and unrecognized cause of primary adrenal insufficiency, and should be included in the differential diagnosis of adrenal hormone deficiency.

Adrenal Glands↗
PubMed1996

Encephalitozoon (Septata) intestinalis: cytologic, histologic, and electron microscopic features of a systemic intestinal pathogen.

Encephalitozoon (Septata) intestinalis affects AIDS patients with CD4 counts <100/microL, causing intestinal and disseminated disease. It must be distinguished from the more common intestinal microsporidian, Enterocytozoon bieneusi, and from other microsporidia of extraintestinal tissues, such as Encephalitozoon hellem and E cuniculi, because clinical manifestations and treatment differ. In this report, the authors describe the diagnostic features of E intestinalis and illustrate all stages of its life cycle as exemplified by a case studied in detail. Spores can be detected by light microscopy in feces, urine, or nasal secretions, but not identified to species. A presumptive tissue diagnosis of E intestinalis can be made if 20 to 50 organisms 1.2-2.5 microm in diameter are seen within vacuoles in enterocytes. The diagnosis is substantiated if organisms also are present in stromal cells. On electron microscopy, the septate parasitophorous vacuole is pathognomonic. E bieneusi occurs only in intestinal and biliary epithelial cells, and never within a vacuole. E hellem and E cuniculi, which are not intestinal pathogens, may cause systemic infection but develop in a nonseptate vacuole.

AIDS-Related Opportunistic Infections↗
PubMed1995

Zygomycosis (mucormycosis) and HIV infection: report of three cases and review.

We report three cases of zygomycosis (mucormycosis) occurring in three individuals infected with the human immunodeficiency virus (HIV) and review 12 other published cases. We present the only two case reports of disseminated zygomycosis in AIDS patients, and the only AIDS patient with renal zygomycosis to survive without nephrectomy, receiving intravenous (i.v.) amphotericin alone. Coinfection with zygomycosis and HIV is rare, occurs primarily in patients with low CD4+ lymphocyte counts, does not always require the usual predisposing conditions for zygomycosis, and may be the presenting opportunistic infection among HIV-infected persons. Transient episodes of neutropenia occurring within 4 months before presentation may be a risk factor for this disease. Zygomycosis may arise in multiple sites including the basal ganglia, cutaneous tissue, kidney, respiratory tract, and may be disseminated. Occurring more commonly in, but not restricted to, injection drug users, it is significantly associated with sites other than basal ganglia in those patients with advanced HIV disease or AIDS. The presenting symptoms are related to the site of involvement, and the illness may develop insidiously or progress rapidly to a fulminant course. Successful therapy usually consists of surgical debridement and intravenous amphotericin B. Overall mortality in this review is 40%, and is significantly associated with sites of disease inaccessible to surgical debridement.

AIDS-Related Opportunistic Infections↗
PubMed1995

Developmental expression and molecular cloning of REMP, a novel retinal epithelial membrane protein.

The retinal pigment epithelium (RPE), like other transport epithelia, has a polarized distribution of membrane and cytoskeletal proteins. The establishment of a polarized phenotype is an essential step in the differentiation of the RPE and the development and maintenance of visual function. Using a monoclonal antibody (MAb 3C4) we have identified a novel membrane protein that is uniquely expressed in chick RPE. We have referred to this protein as REMP for retinal epithelial membrane protein. In these studies we characterized the expression and distribution of this protein during embryonic development and determined its primary structure by cDNA cloning. The developmental expression of REMP was examined by immunocytochemical localization. REMP was first detected in the chick RPE at Embryonic Day 5 (E5) in both apical and basolateral membranes. By E14 the distribution of REMP was restricted to the basolateral surface of the RPE cells. Biochemical fractionation and surface labeling of RPE cells suggested that REMP was an integral protein. The gene encoding REMP was isolated from an E15 chick RPE cDNA library, cloned into lambda gt11, and screened with MAb 3C4. The cDNA was sequenced and found to contain one 1350-bp open reading frame encoding for a 450-amino-acid protein. The deduced amino-acid sequence of REMP shares 32.9% identity with MCT1, a monocarboxylate transporter (Garcia, Goldstein, Pathak, Anderson, and Brown, Cell, 76, 865-873, 1994). By Northern blot analysis, REMP mRNA was detected only in RPE cells. There was an increase in the expression REMP transcript during development but when RPE cells were grown in primary culture the expression of REMP was turned off. The unique expression of REMP in the RPE in vivo would suggest a role for this protein in development and maintenance of normal retinal function.

Amino Acid Sequence↗
PubMed1995

Cimetidine improves the therapeutic/toxic ratio of dapsone in patients on chronic dapsone therapy.

We have previously shown that cimetidine, given concurrently for 2 weeks to patients on chronic dapsone therapy, reduced methaemoglobinaemia by inhibiting the formation of the toxic hydroxylamine metabolite of dapsone. The aim of the present study was to examine the effect of this combination on the benefit/toxic ratio of dapsone over a longer period. Eight patients (six dermatitis herpetiformis, one linear IgA disease, one folliculitis decalvans) on long-term dapsone 50-100 mg daily, took cimetidine 1.6 g daily concurrently for 3 months. At 3-weekly intervals, a clinical assessment was made, plasma dapsone and methaemoglobin were measured, and parameters of oxidative haemolysis were monitored. The dapsone level rose from 2298 +/- 849 ng/ml (mean +/- SD) at baseline to 3006 +/- 1131 ng/ml at week 3 of cimetidine (P < 0.01). This rise in plasma dapsone was sustained during cimetidine administration, falling to 2446 +/- 954 ng/ml when cimetidine was stopped (P < 0.02). The methaemoglobin fell from 5.5 +/- 2.2% (mean +/- SD) at baseline to 3.9 +/- 1.1% at week 3 (P < 0.01), and remained low until week 12, when there was a return to baseline values (P < 0.01). The haemoglobin did not change from the baseline of 12.7 +/- 0.3 g/dl (mean +/- SD), and other parameters of haemolysis were unaltered. There was a fall in the visual analogue score for headache (P < 0.05), but this was not associated with any deterioration in control of the skin disorders. Hence, long-term concurrent cimetidine results in increased plasma dapsone levels without increased haemolysis, and is accompanied by reduced methaemoglobinaemia for more than 2 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗