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T Shea

Publications and source records attributed to T Shea.

At least 19 recordsLinked to original sources
PubMed2001

Crystal structure of the FAD/NADPH-binding domain of rat neuronal nitric-oxide synthase. Comparisons with NADPH-cytochrome P450 oxidoreductase.

Nitric-oxide synthase (NOS) is composed of a C-terminal, flavin-containing reductase domain and an N-terminal, heme-containing oxidase domain. The reductase domain, similar to NADPH-cytochrome P450 reductase, can be further divided into two different flavin-containing domains: (a) the N terminus, FMN-containing portion, and (b) the C terminus FAD- and NADPH-binding portion. The crystal structure of the FAD/NADPH-containing domain of rat neuronal nitric-oxide synthase, complexed with NADP(+), has been determined at 1.9 A resolution. The protein is fully capable of reducing ferricyanide, using NADPH as the electron donor. The overall polypeptide fold of the domain is very similar to that of the corresponding module of NADPH-cytochrome P450 oxidoreductase (CYPOR) and consists of three structural subdomains (from N to C termini): (a) the connecting domain, (b) the FAD-binding domain, and (c) the NADPH-binding domain. A comparison of the structure of the neuronal NOS FAD/NADPH domain and CYPOR reveals the strict conservation of the flavin-binding site, including the tightly bound water molecules, the mode of NADP(+) binding, and the aromatic residue that lies at the re-face of the flavin ring, strongly suggesting that the hydride transfer mechanisms in the two enzymes are very similar. In contrast, the putative FMN domain-binding surface of the NOS protein is less positively charged than that of its CYPOR counterpart, indicating a different nature of interactions between the two flavin domains and a different mode of regulation in electron transfer between the two flavins involving the autoinhibitory element and the C-terminal 33 residues, both of which are absent in CYPOR.

Amino Acid Sequence↗
PubMed2001

Treatment of primary human immunodeficiency virus type 1 infection with potent antiretroviral therapy reduces frequency of rapid progression to AIDS.

Immunologic data supporting immediate antiretroviral therapy in primary human immunodeficiency virus type 1 (HIV-1) infection are emerging; however, clinical benefit has not been demonstrated. The clinical and virologic course of 47 patients who were enrolled from September 1993 through June 1996 and who were not initially treated with potent therapy was compared with the course of 20 patients who immediately began therapy with zidovudine, lamivudine, and indinavir. Demographic and baseline laboratory data were comparable. During 78 weeks of follow-up, the early-treatment cohort showed a reduced frequency of opportunistic infections (5% vs. 21.3%; relative risk, 0.11; P=.02), less frequent progression to AIDS (13% vs. 0%), and significantly less frequent nonopportunistic mucocutaneous disorders and respiratory infections (P<.01). Plasma HIV-1 RNA levels were <50 copies/mL in all patients who continued therapy; however, after 9--12 months, HIV-1 remained detectable in latently infected CD4(+) T cells and in lymph node mononuclear cells. Combination antiretroviral therapy during primary HIV-1 infection demonstrated a decreased frequency of minor opportunistic infections, mucocutaneous disorders, and respiratory infections and reduced progression to AIDS.

AIDS-Related Opportunistic Infections↗
PubMed2001

Sequence analysis of a 101-kilobase plasmid required for agar degradation by a Microscilla isolate.

An agar-degrading marine bacterium identified as a Microscilla species was isolated from coastal California marine sediment. This organism harbored a single 101-kb circular DNA plasmid designated pSD15. The complete nucleotide sequence of pSD15 was obtained, and sequence analysis indicated a number of genes putatively encoding a variety of enzymes involved in polysaccharide utilization. The most striking feature was the occurrence of five putative agarase genes. Loss of the plasmid, which occurred at a surprisingly high frequency, was associated with loss of agarase activity, supporting the sequence analysis results.

Agar↗
PubMed1999

Assay of isoforms of Escherichia coli-expressed nitric oxide synthase.

The techniques described herein have added to our repertoire of experimental approaches for the characterization of the NOSs. These procedures have reinforced our conviction that the NOSs are structurally suited to perform unique functions in their cellular milieux and that these differences have physiological consequences.

Bacterial Proteins↗
PubMed1998

Early establishment of a pool of latently infected, resting CD4(+) T cells during primary HIV-1 infection.

The presence of latently infected, resting CD4(+) T cells carrying replication-competent HIV-1 has been demonstrated in chronically infected individuals who are antiretroviral therapy naive as well as in those who are receiving highly active antiretroviral therapy (HAART). It is not clear, however, whether the establishment of a pool of latently infected CD4(+) T cells can be blocked by early initiation of HAART after primary infection. The present study demonstrates that initiation of HAART in infected individuals as early as 10 days after the onset of symptoms of primary HIV-1 infection did not prevent generation of latently infected, resting CD4(+) T cells carrying integrated HIV-1 DNA as well as infectious HIV-1 despite the successful control of plasma viremia shortly after institution of HAART. Furthermore, there was no correlation between either the duration of HAART at the time of study (range: 0.2-17 months) or the time of initiation of HAART after the onset of symptoms of primary HIV-1 infection (range: 0.3-4 months) and the frequencies of resting CD4(+) T cells carrying either integrated HIV-1 DNA or infectious virus. These results underscore the rapidity with which latent reservoirs are established in primary HIV-1 infection and indicate that it is unlikely that early treatment during primary infection can prevent establishment of a pool of latently infected, resting CD4(+) T cells as long as treatment is initiated after plasma viremia becomes evident.

Anti-HIV Agents↗
PubMed1998

Biological and virologic characteristics of primary HIV infection.

BACKGROUND: The clinical events surrounding acute HIV-1 infection have been well described, but little is known about whether the virologic course of acute HIV-1 infection influences the subsequent progression of disease. OBJECTIVE: To define the virologic natural history of acute and very early HIV infection. DESIGN: Prospective, longitudinal cohort study. SETTING: University of Washington Research Clinic PARTICIPANTS: 74 adults enrolled soon after acquisition of HIV (mean, 69 days). MEASUREMENTS: Plasma HIV-1 RNA levels; quantitative cell cultures; CD4 cell counts; and detailed clinical assessments done at study entry, biweekly for 1 month, monthly for 2 months, and quarterly thereafter. RESULTS: In the first 30 days after acquisition of HIV, HIV-1 RNA levels varied greatly among participants (range, 27,200 to 1.6 x 10(6) copies per mL of plasma). Levels of HIV-1 RNA decreased by a mean of 6.5% per week for the first 120 days and then increased by a mean of 0.15% per week. CD4 cell counts decreased by a mean of 5.2 cells/mm3 per week for the first 160 days and by a mean of 1.9 cells/mm3 per week thereafter (P < 0.01). Disease progressed faster in participants who sought medical care for their acute seroconversion syndrome (P = 0.01) and those who had high plasma HIV-1 RNA levels 120 to 365 days after acquisition (P < 0.01). Peak levels in the first 120 days were not predictive of disease progression. CONCLUSIONS: The variability in viral RNA levels associated with acute HIV-1 infection is greater than previously appreciated. Within 120 days of acquisition, plasma HIV RNA levels rapidly decrease to an inflection point, after which they gradually increase. Virus-host interactions soon after acquisition seem to have a major influence on the long-term outcome of HIV-1 disease.

Adult↗
PubMed1998

Is the course of panic disorder the same in women and men?

OBJECTIVE: Panic disorder with or without agoraphobia has a chronic relapsing course. Factors associated with poor outcome include early onset of illness and phobic avoidance. Several, but not all, authors have found a worse clinical course for women. Using observational, longitudinal data from the Harvard/Brown Anxiety Disorders Research Program, the authors analyzed remission and symptom recurrence rates in panic patients with respect to sex. METHOD: Male and female patients (N = 412) in an episode of panic with or without agoraphobia were assessed by structured interview and prospectively followed for up to 5 years. Data on remission, symptom recurrence, and comorbid psychiatric conditions for each sex were compared. RESULTS: There were no significant differences between men and women in panic symptoms or level of severity at baseline. Women were more likely to have panic with agoraphobia (85% versus 75%), while men were more likely to have uncomplicated panic (25% versus 15%). The rates of remission for panic with or without agoraphobia at 5 years were equivalent in men and women (39%). Of the subjects who achieved remission, 25% of the women and 15% of the men reexperienced symptoms by 6 months. Recurrence of panic symptoms continued to be higher in women (82%) than men (51%) during the follow-up period and was not influenced by concurrent agoraphobia. CONCLUSIONS: This study extends previous findings by showing that not only are women more likely to have panic with concurrent agoraphobia, but they are more likely than men to suffer a recurrence of panic symptoms after remission of panic.

Age of Onset↗
PubMed1997

Cytotoxic-T-cell responses, viral load, and disease progression in early human immunodeficiency virus type 1 infection.

BACKGROUND: Early in human immunodeficiency virus type 1 (HIV-1) infection there is a decline in viral replication that has been attributed to host immunity, but the components of this response, particularly the ability of cytotoxic T lymphocytes to control viral burden and influence the outcome of disease, are poorly understood. METHODS: We prospectively studied 33 patients with primary HIV-1 infection for HIV-specific activated cytotoxic T lymphocytes and memory cytotoxic T lymphocytes and compared these lymphocyte responses with changes in viral load and clinical status over the subsequent 18 to 24 months. RESULTS: Soon after infection, activated HIV-specific cytotoxic T lymphocytes, mediated primarily by CD8+ cells, were detected in 17 of 23 patients (74 percent). Memory cytotoxic T lymphocytes were found in 6 of 6 patients tested (100 percent) during the first three months of infection and in 17 of 21 patients (81 percent) tested during the first six months. The frequencies of memory cytotoxic T lymphocytes varied markedly over time, but overall they declined over the first 6 to 8 months and then stabilized over the next 12 to 18 months. The patients with higher frequencies of Env-specific memory cytotoxic T lymphocytes had a median level of plasma HIV-1 RNA about one third that of the patients with lower frequencies, (median number of RNA copies per milliliter, 22,000 vs. 62,000; P=0.006). Patients with low frequencies of Env-specific memory cytotoxic T lymphocytes (or none) in early infection had a more rapid decline to less than 300 CD4+ cells per cubic millimeter (P = 0.05). CONCLUSIONS: In early HIV-1 infection, the induction of memory cytotoxic T lymphocytes, particularly those specific for Env, helps control viral replication and is associated with slower declines in CD4+ cell counts. Host cytolytic effector responses appear to delay the progression of HIV-1 disease.

Adult↗
PubMed1997

Lithium and recurrence in a long-term follow-up of bipolar affective disorder.

BACKGROUND: Though previous studies have clearly shown that lithium affords prophylaxis in bipolar affective disorder, these studies have not demonstrated the persistence of this prophylactic effect beyond the first year of recovery. METHODS: One hundred and eighty-one patients with bipolar affective disorder recovered during 5 years of semi-annual follow-up. After 8 weeks of recovery, 139 were taking lithium prophylaxis and 42 were not. Analyses used drug status (lithium v. no-lithium) as a censoring variable to compare these two groups by interval-specific probabilities of recurrence. RESULTS: Recurrence was initially less likely in the lithium group but interval-specific probabilities of recurrence did not consistently favour either group after the first 32 weeks of recovery. CONCLUSIONS: Biases in treatment decisions may have both reduced the size and altered the specificity of the lithium effects seen here. Nevertheless, the apparent transience of lithium prophylactic effects is unexplained and may reflect important, physiological differences between relapse and recurrence. This possibility invites a controlled lithium discontinuation study, with gradual taper, of patients who have had at least 8 months of sustained euthymia.

Adult↗
PubMed1996

Clinical and epidemiologic features of primary HIV infection.

BACKGROUND: The acute clinical events surrounding the acquisition of human immunodeficiency virus (HIV) have not been well characterized. OBJECTIVE: To further define the clinical and epidemiologic presentation of primary HIV infection. DESIGN: Descriptive cohort study. SETTING: University research clinic. PATIENTS: 46 adults (43 men and 3 women) with primary HIV infection who enrolled in the study a median of 51 days after HIV seroconversion. MEASUREMENTS: Documentation of recent HIV seroconversion. Standardized collection of demographic characteristics and sexual contact history, results of tests for HIV RNA, HIV culture, and T-cell subsets. RESULTS: 41 of 46 patients (89%) developed an acute retroviral syndrome. Primary HIV infection was infrequently diagnosed at the initial medical encounter, even in persons enrolled in routine HIV screening programs. Median numbers of sexual partners 6 months and 1 month before acquisition of HIV were three and one, respectively; 21 patients (46%) reported having had only one partner in the month before seroconversion. Of the 12 patients who could identify the precise date of and activity leading to seroconversion, 4 reported having only oral-genital contact. CONCLUSIONS: Primary HIV infection causes a recognizable clinical syndrome that is often underdiagnosed, even in persons enrolled in a program of routine surveillance for HIV infection. Frequency of sexual contact and overall numbers of sexual partners in this group of homosexual men who acquired HIV were markedly lower than those seen a decade ago. Acquisition of HIV does occur, even in persons with relatively few sexual partners. Increased attention to oral-genital contact as a means of acquiring HIV appears to be warranted.

Adult↗
PubMed1996

North American Multicenter Study on flow cytometric enumeration of CD34+ hematopoietic stem cells.

Transplant centers often rely on CD34+ cell quantitation by flow cytometry to ensure adequacy of hematopoietic progenitor cell collection. Because of variation in interpretation, a lack of interlaboratory proficiency studies, and no generally accepted methodology, comparison of CD34 data from site to site is difficult. Twenty-one samples from marrow and peripheral blood stem cell collections were shipped to 10 participating North American laboratories for analysis. Duplicate samples were included to assess reproducibility. Participants were surveyed for methodology. Three centers had previously attempted to standardize their methodology among themselves. The variability observed in the CD34 values ranged from a max/min. reported value per sample of 2.9 to 749 (median 76). Exclusion of two outlying sites reduced the variability of results to 1.2 to 27 (median 3.1). Variation among the three standardized sites ranged from 1.2 to 4.4 (median 1.6). Overall reproducibility (excluding the outlying sites B and G) ranged from a minimum of 0-16.5 (percent mean difference) for site C to a maximum of 4.1-133 for site H. Strategies for gating were found to largely influence results. We observed an alarming variation among the CD34 cell counts reported from different laboratories. Standardization substantially reduced observed variation. The need for standardized methodology, reporting, quality control, and proficiency testing is underscored by these findings.

Antigens, CD34↗
PubMed1995

Crystallization and preliminary x-ray studies of NADPH-cytochrome P450 reductase.

NADPH-cytochrome P450 reductase (CPR; NADPH:ferrihemoprotein reductase, EC 1.6.2.4) catalyzes the transfer of electrons to all known microsomal cytochromes P450. CPR is unique in that it is one of only two mammalian enzymes known to contain both flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), the other being the various isoforms of nitric oxide synthase. Similarities in amino acid sequence and in functional domain arrangement with other key flavoproteins, including nitric oxide synthase, make CPR an excellent prototype for studies of interactions between two flavin cofactors. We have obtained diffraction-quality crystals of rat liver CPR, expressed in Escherichia coli and solubilized by limited proteolysis with trypsin. The crystals were grown in Hepes buffer (pH 7.0), containing polyethylene glycol 4500 and NaCl. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell dimensions a = 103.3 A, b = 116.1 A, and c = 120.4 A. If we assume that there are two molecules of the 72-kDa CPR polypeptide per asymmetric unit, the calculated value of Vm is 2.54 A3/Da.

Amino Acid Sequence↗
PubMed1995

Characteristics and significance of untreated major depressive disorder.

OBJECTIVE: This study sought to describe the characteristics and consequences of untreated major depressive disorder. METHOD: As part of a family study of probands with major affective disorders, raters assessed 3,119 first-degree relatives, spouses, and comparison subjects. When 2,237 (71.7%) of these individuals were reassessed 6 years later, 547 had experienced episodes of major depressive disorder in the interval. Those who had sought any form of treatment for any episode of major depressive disorder in the interval were compared, by baseline demographic characteristics and clinical features of their worst episodes of major depressive disorder, to those who had not. Individuals who had had untreated major depressive disorder were then compared, by changes in socioeconomic status and by levels of psychosocial impairment at follow-up, to a matched group with no major depressive disorder in the interval. RESULTS: The worst episodes of 313 treated individuals, compared to those of 234 untreated individuals, were characterized by older age, symptoms of the endogenous subtype, longer durations, and the presence of disruption in role function. Each of these factors contributed independently to the distinction between treated and untreated episodes. Untreated individuals experienced significant psychosocial impairment on follow-up but did not show the economic disadvantages shown elsewhere for probands who began follow-up as they sought treatment at tertiary medical centers. CONCLUSIONS: These data suggest that illness characteristics and age determine the decision to seek treatment for major depressive disorder. Untreated depression is apparently associated with long-standing psychosocial difficulties but not with serious economic consequences.

Adolescent↗
PubMed1995

A clinical and pharmacokinetic study of high-dose carboplatin, paclitaxel, granulocyte colony-stimulating factor, and peripheral blood stem cells in patients with unresectable or metastatic cancer.

We have developed a regimen incorporating multiple cycles of high-dose carboplatin and fixed-dose paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) with granulocyte colony-stimulating factor and peripheral blood stem cell support given every 21 days for up to four cycles. Our phase I study of this regimen has treated 26 patients with good performance status and histologically documented unresectable or metastatic carcinoma, sarcoma, or melanoma, 21 of whom received all planned courses every 21 days. Paclitaxel 250 mg/m2 was infused over 24 hours, followed by a 1-hour carboplatin infusion, with doses escalated between area under the concentration-time curve (AUC) targets of 8 and 20. Considering the carboplatin doses administered (two to three times those generally achieved with growth factor support), toxicity has been relatively modest. The median duration of grade 4 neutropenia and thrombocytopenia was not significantly different between the AUCs of 8 and 18, which proved to be the maximum tolerated carboplatin dose. Twelve courses were associated with hospitalization for neutropenic fever or catheter-related thrombophlebitis. One treatment-related death occurred, and severe toxicity caused withdrawal of two patients treated at the AUC of 20. Peripheral neuropathy was the most common serious nonhematologic complication. Pharmacokinetic analysis showed significantly lower measured versus predicted AUC values. Among 25 evaluable patients, preliminary results show one complete response (ovarian cancer) and 11 partial responses, including four in patients with non-small cell lung cancer. Additional issues to be addressed include the effect of a shorter (or longer) paclitaxel infusion on the carboplatin AUC (and the incidence of toxicity) and whether the discrepancy between actual and predicted AUCs (greater in our study than reported elsewhere) is due to the variability of creatinine clearance-determined glomerular filtration rate or to altered carboplatin pharmacokinetics when a short high-dose infusion follows paclitaxel. Additional patients are being accrued at the AUC of 18.

Adult↗
PubMed1994

The long-term stability of depressive subtypes.

OBJECTIVE: This study used the concept of diagnostic stability to examine the validity of three subtypes of major depression. METHOD: Patients with major depressive disorder (N = 424) were assigned baseline diagnoses according to structured interviews and the Research Diagnostic Criteria. Follow-up evaluations took place at 6-month intervals over the next 5 years and annually for an additional 3 years. During this period 424, 246, 163, and 96 of the patients who had recovered from the index episode had one, two, three, and four recurrences, respectively, of major depressive disorder. The kappa statistic was used to quantify the likelihood that patients with the psychotic, agitated/retarded, or endogenous subtype of depression in a given episode would again manifest that subtype in subsequent episodes. RESULTS: The psychotic subtype showed the most enduring diagnostic stability across multiple subsequent episodes. Even after three intervening episodes, patients with baseline psychotic major depression were five times more likely to develop a psychotic depression than were other depressed patients. For all three subtypes, diagnostic stability was greater for contiguous episodes than for noncontiguous episodes. Psychotic, agitated/retarded, and endogenous subtypes showed significant stability after control for the bipolar/unipolar and primary/secondary distinctions. The endogenous subtype was stable among patients with primary depression but not among those with secondary depression. CONCLUSIONS: The psychotic subtype was the most valid of the subtypes tested from the perspective of diagnostic stability. The fact that stability across adjacent episodes exceeded stability across more distantly spaced episodes may reflect state-dependent determinants, and these are likely to vary by subtype.

Bipolar Disorder↗