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Biomedical subjects

R M Tucker

Publications and source records attributed to R M Tucker.

At least 19 recordsLinked to original sources
PubMed1996

Directed mutagenesis of YAC-cloned DNA using a rapid, PCR-based screening protocol.

We have developed a system which facilitates the rapid modification of yeast artificial chromosome (YAC) insert DNA. Specific modifications, such as deletions, insertions and point mutations, can be generated by a two-step allele replacement method using the yeast translational suppressor, SUP4-o, as both a positive and negative selection. The introduction of the SUP4-o gene was successful in 4 out of 24 selected transformant colonies, while the subsequent homologous elimination occurred in 2 out of 30 colonies. The use of a simple, short-range PCR assay rapidly identified the correct events among the genetically selected isolates and should be generally applicable to YAC modifications.

Animals↗
PubMed1996

Transgenic mice for the establishment of histidinol-resistant embryonic fibroblast feeder layers.

Gene targeting in mouse embryonic stem cells generates mutations by replacing an endogenous chromosomal region with a copy disrupted by a selectable genetic marker. The most commonly used selectable marker is the bacterial neo(r) gene, which confers resistance in mammalian cells to the antibiotic G418. Use of an alternative selectable marker, the Salmonella typhimurium gene hisD, should provide expanded applications for gene targeting. The hisD gene encodes the protein histidinol dehydrogenase, which catalyzes the conversion of histidinol to the amino acid histidine. Histidinol is toxic to mammalian cells, while histidine is an essential mammalian amino acid. Consequently, growth selection in cultures with media containing histidinol in place of histidine occurs by both histidine starvation and histidinol poisoning. The hisD selection is being tested for potential use in gene targeting experiments with mouse embryonic stem (ES) cells. Currently, most successful gene targeting experiments use primary embryonic fibroblast feeder layers, which assist in the maintenance of the pluripotential state of the embryonic stem cells. To support ES cell stability under histidinol selection, mice transgenic for the S. typhimurium hisD gene have been produced and used to generate embryonic fibroblast feeder cells. The transgenic embryonic fibroblasts survive under a wide range of histidinol-containing growth conditions and support growth of ES cell cultures.

Alcohol Oxidoreductases↗
PubMed1994

Treatment of coccidioidomycosis with SCH 39304.

A new oral triazole antifungal, SCH 39304, was administered to 54 patients with progressive infections due to Coccidioides immitis from six collaborating centers. Patients were grouped according to site of infection including chronic pulmonary (25), bone/joint (17) and skin/soft tissue (12). The median age was 40 years; 83% were male, 52% white, 13% HIV-infected and 35% had failed previous therapy. The majority of patients were treated with either 100 mg or 200 mg day-1. One patient on renal dialysis received 300 mg day-1. Baseline abnormalities were reassessed for evidence of efficacy every 4 months and expressed in a standardized scoring system. Cumulative overall response rates at 4, 8 and 12 months were 7%, 36% and 66% respectively. Twelve month response rates by disease were 77% (pulmonary), 62% (skin/soft tissue) and 31% (bone/joint). Fifteen patients failed therapy although seven of these were still on treatment when the study was discontinued. Two failed due to toxicity. Possible symptoms or signs of toxicity occurred in 24 (44%) patients and were generally mild. SCH 39304 is an effective and well tolerated therapy for progressive forms of coccidioidomycosis.

Administration, Oral↗
PubMed1992

Interaction of azoles with rifampin, phenytoin, and carbamazepine: in vitro and clinical observations.

Twelve patients receiving therapy with an azole agent (ketoconazole, itraconazole, and/or fluconazole) for systemic mycoses experienced drug interactions with rifampin, phenytoin, and/or carbamazepine resulting in substantial decreases in azole concentrations in serum. All four patients receiving azoles and concurrent phenytoin and/or carbamazepine failed to respond to treatment or suffered a relapse of their fungal infection. Four of five patients with cryptococcosis who received itraconazole and rifampin responded despite decreases in their serum itraconazole concentrations; synergy between itraconazole and rifampin was documented by in vitro analysis of inhibition and of killing of Cryptococcus neoformans isolates from all patients receiving this combination. In contrast, two patients with coccidioidomycosis failed to respond to itraconazole/rifampin. Moreover, two patients with cryptococcosis suffered a relapse or persistence of seborrheic dermatitis while receiving itraconazole/rifampin. The latter combination showed synergy in vitro in the inhibition of the mycelial phase of Coccidioides immitis and, to a lesser extent, of the pathogenic spherule phase of this fungus; synergy in the killing of C. immitis was not noted, nor was synergy seen against Malassezia furfur, the purported etiologic agent of seborrheic dermatitis. These findings illustrate several drug interactions that may affect clinical outcome and that must be considered in the management of antifungal therapy.

Adult↗
PubMed1990

Itraconazole therapy for chronic coccidioidal meningitis.

STUDY OBJECTIVE: To assess the efficacy of orally administered itraconazole in the treatment of coccidioidal meningitis. DESIGN: Prospective, nonrandomized open trial. SETTING: Multicenter trial at an urban county hospital, a university referral center, and referring institutions. PATIENTS: Ten patients with culture or serologic evidence of coccidioidal meningitis refractory to standard therapy. Patients receiving other systemic antifungal therapy were excluded. INTERVENTION: Itraconazole was administered orally at doses of 300 to 400 mg/d for a median duration of 10 months. Disease activity and drug efficacy were evaluated at initiation of therapy and at the most recent follow-up using a standardized scoring system. MEASUREMENTS AND MAIN RESULTS: Eight of ten patients are evaluable. Of five patients receiving itraconazole as sole therapy, four have responded. All three patients receiving intrathecal amphotericin B have had that therapy discontinued and have no evidence of active disease in the absence of intrathecal therapy. Toxicity has been minimal; one patient had mild nausea. CONCLUSIONS: Itraconazole shows impressive activity in this series of patients with refractory coccidioidal meningitis. Itraconazole in this and other fungal meningitides should be evaluated further.

Adolescent↗
PubMed1990

Itraconazole treatment of phaeohyphomycosis.

Nineteen patients with phaeohyphomycosis were treated with itraconazole. Of these, 17 were assessable for clinical outcome. Of these, two had received no prior therapy, five had failed amphotericin B therapy, four had failed ketoconazole or miconazole therapy, and five had failed both amphotericin B and azole therapy. One patient had received only prior surgical intervention. Fungi of seven different genera caused disease of the skin in nine patients, soft tissue in nine, sinuses in eight, bone in five, joints in two, and lungs in two. Itraconazole was given in dosages ranging from 50 to 600 mg/day for 1 to 48 months. Clinical improvement or remission occurred in nine patients. Two patients have had stabilization of disease. Six patients failed treatment, one had a relapse after initially successful treatment. Itraconazole appears to be highly effective in some patients with phaeohyphomycosis, including patients refractory to other antifungal agents.

Adult↗
PubMed1990

Itraconazole therapy for nonmeningeal coccidioidomycosis: clinical and laboratory observations.

Itraconazole, a new oral triazole antifungal agent, was administered in 75 courses to patients with chronic coccidioidomycosis at dosages of 50 to 400 mg/day for a median duration of 10 months. Assessment of efficacy was made with a standardized scoring system. Responses were seen in 42 of 58 assessable courses (72%). Nonresponse occurred exclusively in patients who had failed previous therapy and was most common in pulmonary disease. Toxicity was minimal at the doses studied. Pharmacokinetic analysis of itraconazole in serum at steady state showed negligible circadian variation; differences in serum concentrations among patients were large. Clinical isolates of Coccidioides immitis showed uniform in vitro susceptibility to itraconazole. Itraconazole shows impressive activity in this series of patients with refractory coccidioidomycosis. Further evaluation of itraconazole in this and in other systemic mycoses is in order.

Adolescent↗
PubMed1990

Itraconazole in opportunistic mycoses: cryptococcosis and aspergillosis.

Striking results were obtained with oral itraconazole therapy in two opportunistic mycoses. Of 28 patients with cryptococcal meningitis, 18 achieved complete responses, including 16 of 24 patients with acquired immunodeficiency syndrome. Other manifestations of cryptococcosis were similarly responsive. In aspergillosis 12 of 15 patients responded, including 8 of 10 immunocompromised hosts. These patients included those with invasive pulmonary disease (4/5), skeletal disease (2/2), pleural disease (1/2), and pericardial, sinus, mastoid, hepatosplenic, or nail disease (1/1). These results with itraconazole compare favorably to conventional (parenteral) therapy, and toxicity was minimal. This suggests that comparative trials are now in order.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Adverse events associated with itraconazole in 189 patients on chronic therapy.

Itraconazole was administered at doses of 50-400 mg/day to 189 patients with a variety of systemic mycoses for a median of five months. Adverse reactions possibly due to itraconazole were seen in 74 patients (39%). Mild gastrointestinal reactions were most common; other reactions including hypertriglyceridaemia, hypokalaemia and liver enzyme elevations occurred less frequently. No fatal reactions have been noted and toxicity has rarely led to a discontinuation of therapy. Chronic therapy with itraconazole appears well tolerated by the majority of patients.

Adolescent↗
PubMed1990

Low-dose dapsone prophylaxis of Pneumocystis carinii pneumonia in AIDS and AIDS-related complex.

The efficacy, toxicity and cost of orally administered dapsone (50-100 mg/day) for prophylaxis of Pneumocystis carinii pneumonia (PCP) were evaluated in 30 patients with AIDS or AIDS-related complex (ARC). Six patients received primary and 24 secondary prophylaxis. Ten patients received a maximum dose of 100 mg/day and 20 a maximum of 50 mg/day for a median duration of 19 weeks; 22 of the 30 patients continue to receive prophylaxis as of May 1989. Four patients have died, none of pneumocystis infection. One patient with AIDS suffered a mild relapse while receiving 50 mg/day. Hematologic toxicity was mild and could not be definitively attributed to dapsone therapy; rash due to dapsone was documented in two patients. A review of 33 patients at our institution with a history of PCP who received no prophylaxis demonstrated seven relapses, three of which were fatal. Cost analysis revealed a significant advantage for oral dapsone over aerosolized pentamidine.

AIDS-Related Complex↗
PubMed1989

Treatment of invasive aspergillosis with itraconazole.

PURPOSE: Invasive aspergillosis in the immunocompromised host is one of the most difficult therapeutic problems. Itraconazole, a new oral triazole, is inhibitory as well as fungicidal against Aspergillus species in vitro. It is active against Aspergillus infections in animal models. We present our experience with itraconazole therapy of 21 patients with aspergillosis. PATIENTS AND METHODS: Eighteen of the 21 patients received 400 mg of itraconazole orally per day; the other three received 100 to 200 mg daily. Serum concentrations of itraconazole were measured and susceptibility testing was performed according to previously described methods. RESULTS: Of 15 evaluable patients, responses were produced in 12. Four of five with invasive pulmonary disease, two of two with skeletal disease, one of two with pleural disease, one of one with pericardial, sinus, mastoid, or hepatosplenic aspergillosis, and one of one with onychomycosis responded. One patient with carotid artery disease did not show a response, although results of cultures were negative at autopsy. One responder with joint disease had a possible relapse three months after completing 12 months of therapy. Ten of these patients were immunocompromised (including four with neutropenia and two renal transplant recipients) and eight of these responded. Side effects with itraconazole, in contrast to previously available therapy, were rare. CONCLUSION: This experience suggests itraconazole may be an important advance in the therapy of aspergillosis.

Adult↗
PubMed1989

The seroprevalence of cytomegalovirus among Virginia State prisoners.

A prevalence serosurvey of adult male prisoners entering the Virginia State Prison was conducted to evaluate the epidemiology of cytomegalovirus within this population. Four hundred and forty-five (97%) of 459 male inmates provided serum for analysis and 427 completed a detailed demographic questionnaire. Sera were tested for cytomegalovirus by passive latex agglutination and 64% were reactive. Multivariate discriminant analysis showed an independent association of seropositivity with age, non-white race, and a history of gonorrhea. There was no apparent contribution from admitted homosexual contact though this may have been under-reported. There was no correlation of seropositivity with intravenous drug use or with the length or number of prior incarcerations. Prisoners possess the same correlates for cytomegalovirus seropositivity as the general adult population; past imprisonment did not independently contribute to cytomegalovirus seropositivity.

Adult↗
PubMed1989

Cytomegalovirus and appendiceal perforation in a patient with acquired immunodeficiency syndrome.

We have reported the case of a patient with AIDS who had appendiceal perforation and periappendiceal abscess. Extensive infection with cytomegalovirus was found in the appendix; no other pathogen could be implicated in the perforation. This case emphasizes the broad spectrum of disease due to cytomegalovirus, particularly in patients with AIDS and other immunodeficiencies.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Activity of ICI 195,739, a new oral triazole, compared with that of ketoconazole in the therapy of experimental murine blastomycosis.

ICI 195,739, a novel orally active triazole, proved 50 times as potent as ketoconazole, produced a clinical cure, and completely eradicated residual infection in a murine model of pulmonary blastomycosis. No other previously tested azole has shown similar activity. Fungicidal activity against Blastomyces dermatitidis was seen in vitro at concentrations 1/40 of those achieved in serum with protective doses.

Animals↗
PubMed1989

Itraconazole therapy for cryptococcal meningitis and cryptococcosis.

We studied the efficacy of itraconazole, a new oral triazole, in 33 patients (32 were immunocompromised) with cryptococcosis. Diagnoses included cryptococcal meningitis (24 patients), cryptococcemia (19 patients), cryptococcuria (4 patients), osteomyelitis (1 patient), pulmonary cryptococcosis (1 patient), and soft-tissue cryptococcosis (2 patients). Twenty-six patients had the acquired immunodeficiency syndrome, and 4 were transplant recipients. Therapy (200 mg two times per day) was monitored by clinical response, culture, and cryptococcal antigen testing. Cryptococcemia was abolished in 10 (100%) of 10 assessable patients; clinical abnormalities also cleared. Thirteen (65%) of 20 assessable patients with cryptococcal meningitis had complete responses (clinical resolution and negative cultures), 5 (25%) had partial responses, and therapy failed in 2 (10%). Ten (71%) of 14 patients with the acquired immunodeficiency syndrome who had meningitis and were treated with itraconazole as their sole therapy had complete responses, 3 (21%) had partial responses, and therapy failed in 1 (7%). Partial responses or failures were all associated with the failure of previous therapy, severe disease, low serum itraconazole concentrations, or a resistant organism. Noncompliance was associated with relapse (4 patients). Meningitis recrudesced in 3 (20%) of 15 patients who responded to therapy. All 4 patients with pulmonary cryptococcosis, soft-tissue cryptococcosis, or osteomyelitis responded to therapy (100%). Cryptococcuria was abolished in 3 (60%) of 5 assessable patients. The median survival of the 20 patients with the acquired immunodeficiency syndrome who had meningitis exceeded 10.5 months at this writing. Overall results compare favorably with amphotericin B therapy with or without flucytosine. Forty of 44 isolates of Cryptococcus neoformans were susceptible in vitro to itraconazole (minimum inhibitory concentration less than or equal to 3.13 mg/L), 3 were borderline (minimum inhibitory concentration, 6.25 mg/L), and 1 was resistant (minimum inhibitory concentration, 12.5 mg/L). As itraconazole does not penetrate cerebrospinal fluid, the meningitis results are noteworthy and suggest that meningeal and parenchymal penetration is critical. Itraconazole is promising for the treatment of cryptococcosis in patients with and without the acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Treatment of mycoses with itraconazole.

The efficacy of itraconazole, a new oral triazole, was evaluated at doses of 50-400 mg/day in 64 courses: 39 with coccidioidomycosis, and 25 with other mycoses. Among patients with coccidioidomycosis, 21 had pulmonary disease; 10, bone and joint; 8, lymphatic; 6, skin and soft tissue; 3, meningeal; and 1, urogenital. After a mean of 7.1 months of treatment, 17 of 27 evaluable courses (63%) have shown a full response; 8 (30%), a partial response; and 2 (7%), no response. Response to treatment was higher in patients with a shorter duration of illness and in patients with no previous treatment. After a mean of 12 months of treatment, two of five responders off therapy have relapsed. In patients with other mycoses, diagnoses include aspergillosis in six patients; histoplasmosis and tinea in three each; alternariosis, candidiasis, cryptococcosis, blastomycosis, and chromomycosis in two each; and pseudallescheriosis in one. After a mean of 9.4 months of treatment, 14 of 23 evaluable patients (61%) have shown a full response; 2 (8%), a partial response; and 7 (30%), no response. All patients with histoplasmosis and blastomycosis have responded to therapy. There are no relapses among five evaluable responders after a mean of 9.2 months off therapy. In 512 patient months of therapy, toxicity has been minimal. Mean serum levels in patients receiving 200 mg twice daily range from 3.9 to 5.9 micrograms/ml for 8 hr after dosing, with a peak at 7 hr and wide interpatient variability. Itraconazole is well tolerated and has continued to demonstrate efficacy in the treatment of a variety of systemic and superficial mycoses.

Adult↗