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Biomedical subjects

K Herzig

Publications and source records attributed to K Herzig.

12 recordsLinked to original sources
PubMed2004

The mysteries and demands of HIV care: qualitative analyses of HIV specialists' views on their expertise.

To deepen our understanding of the mysteries and demands associated with HIV care and to inform the debate about HIV specialization, we conducted in-depth interviews with a purposive sample of 20 identified HIV specialists in the San Francisco Bay Area. Participants were from several medical specialties and reported a median of 50% of their time spent in HIV patient care. Through constant comparison, a template of open codes was constructed to identify themes that emerged from the data. Data were analyzed according to the conventions of qualitative research and revealed six interrelated themes: (1) coping with uncertainty and rapid change: being 'comfortable with mystery'; (2) the powerful role of experience; (3) the dual faces of knowledge: 'knowing the patient' and 'knowing the facts'; (4) the dual faces of passion: challenge and calling; (5) stress and burnout; and (6) the relationship between academia and 'the trenches'. The themes underscore the dual dimensions of HIV care: providers must interweave the 'half-baked' science about drug therapies, side effects and drug interactions with the psychosocial and lifestyle factors of the patient. They also provide insight into quantitative findings linking greater HIV experience with better patient outcomes and suggest that providers need skills associated with generalist and specialist training, a phenomenon that argues for a 'special' specialty for HIV care.

Attitude of Health Personnel↗
PubMed2001

Identification of CCK-B/gastrin receptor splice variants in human peripheral blood mononuclear cells.

There is increasing evidence for a direct interaction of the enteric nervous and immune system. Receptors for neuropeptides such as VIP, somatostatin, and substance P have been characterised in human immuno-haematopoietic cells but little is known about the functional significance and expression of receptors for cholecystokinin (CCK) on cells of the immune system. There are only few studies that describe the expression of CCK receptors on human leukaemia-derived cell lines but the receptor structure and function in normal leukocytes have not been clearly established. We therefore sought to determine CCK receptor expression, structure, and function in nontransformed human peripheral blood mononuclear cells.Full-length cDNA clones encoding the human CCK-A and CCK-B/gastrin receptor are expressed in peripheral blood mononuclear cells from healthy volunteers without haematopoietic malignancy. In addition to wild-type CCK-B/gastrin receptor cDNAs, we isolated a splice variant with an in frame insertion of 69 amino acids within its putative third intracellular receptor loop. Dideoxy sequence analysis revealed that the cDNA of this splice variant comprises exons 1-4 but retains intron 4 (207 bp) in the absence of mutations within the splice donor sites. Transient expression of this splice variant in COS-7 cells reveals wild-type affinity for CCK-8, Gastrin-17, and antagonist L-365,260. Affinity for glycine-extended gastrin-17 was not increased when compared to the wild-type CCK-B/gastrin receptor. In vitro, gastrin decreased 3H-thymidine labelling in phytohaemagglutinin-pretreated mononuclear cells at a half-maximally effective concentration of 1.5 nM. We also isolated a cDNA encoding another splice variant of the CCK-B/gastrin receptor with a 158 bp deletion of the entire exon 4 sequence. We conclude that wild-type transcripts of both CCK receptor subtypes and splice variants of the CCK-B/gastrin receptor are expressed in nontransformed human mononuclear cells and that gastrin exhibits antiproliferative effects.

Alternative Splicing↗
PubMed2000

A comparison of the effects of dialysis and renal transplantation on the survival of older uremic patients.

BACKGROUND: Patients over age 60 constitute half of all new patients accepted into the renal replacement therapy programs in Australia. However, the optimal treatment of their end-stage renal disease remains controversial. The aim of the present study was to compare survival for dialysis and renal transplantation in older patients who were rigorously screened and considered eligible for transplantation. METHODS: The study cohort consisted of 174 consecutive patients over 60 who were accepted on to the Queensland cadaveric renal transplant waiting list between January 1, 1993 and December 31, 1997. Follow-up was terminated on October 1, 1998. Data were analyzed on an intention-to-transplant basis using a Cox regression model with time-varying explanatory variables. An alternative survival analysis was also performed, in which patients no longer considered suitable for transplantation were censored at the time of their removal from the waiting list. RESULTS: There were 67 patients receiving a renal transplant, whereas the other 107 continued to undergo dialysis. These two groups were well matched at baseline with respect to age, gender, body mass index, renal disease etiology, comorbid illnesses, and dialysis duration and modality. The overall mortality rate was 0.096 per patient-year (0.131 for dialysis and 0.029 for transplant, P<0.001). Respective 1-, 3- and 5-year survivals were 92%, 62%, and 27% for the dialysis group and 98%, 95%, and 90% (P<0.01) for the transplant group. Patients in the transplant group had an adjusted hazard ratio 0.16 times that of the dialysis group (95% confidence interval 0.06-0.42). If patients were censored at the time of their withdrawal from the transplant waiting list, the adjusted hazard ratio was 0.24 (95% confidence interval 0.09-0.69). CONCLUSIONS: Renal transplantation seems to confer a substantial survival advantage over dialysis in patients with end-stage renal failure who are rigorously screened and considered suitable for renal transplantation.

Aged↗
PubMed2000

Functional expression of HGF and its receptor in human colorectal cancer.

BACKGROUND: Hepatocyte growth factor (HGF) stimulates proliferation, migration and morphogenesis of epithelial cells by specific binding to its receptor c-met. Overexpression of HGF or c-met has been reported for human gastric or pancreatic cancer. In colorectal cancer overexpression of c-met but not HGF has been shown. However, elevated HGF serum levels have been detected in colorectal cancer patients. Therefore, the present study was performed to investigate expression patterns of both c-met and HGF in colorectal cancers and metastasis in comparison to normal mucosa. Furthermore, the mitogenic actions of HGF on colorectal cancer cells were studied in vitro. METHODS: Expression of c-met and HGF were analyzed by RT-PCR and Western blotting and localized in the tissues utilizing immunohistochemistry. Mitogenic effects of HGF were determined in four human colon cancer cell lines by (3)H-thymidine incorporation studies. RESULTS: C-met and HGF mRNA were detectable in 60% of the normal specimen, but in the majority of cancer samples, and in just 33% of the liver metastasis. In cancer samples a coexpression of c-met and HGF was detected in 77% of the specimens. The extent of protein expression of receptor and ligand correlated with the mRNA expression. Moreover, c-met protein expression was increased 2- to 3-fold in colorectal cancers. C-met was detected in cells of epithelial origin, whereas HGF was expressed by mesenchymal cells. In vitro, HGF significantly stimulated cell growth in all four cell lines. CONCLUSION: Overexpression of c-met protein in colorectal cancers is combined with an expression of HGF in the majority of cases suggesting a paracrine manner of growth enhancement, while only a weak expression of c-met or HGF was detected in metastatic tissues.

Adenocarcinoma↗
PubMed1999

Perceptions of health care professionals and patients about the risk of HIV transmission through oral sex: a qualitative study.

We explored health care professionals' beliefs and methods for counseling patients about risks for transmitting human immunodeficiency virus (HIV) through oral sex and HIV-seropositive patients' beliefs and practices regarding oral sex behavior. Health care professionals used divergent counseling strategies, avoided specific recommendations, and expressed ambivalence about recommending barrier protection for oral sex. Patients expressed differing beliefs about oral sex risk; the majority have engaged in unprotected oral sex since diagnosis. Few professionals or patients mentioned oral sex risk for other sexually transmitted diseases (STDs), which can be cofactors for HIV. Although scientific evidence indicates a potential risk for transmitting HIV via oral sex, and patients in our sample want more information about this risk, the health care professionals we interviewed have adopted a largely noncommittal approach to communicating potential risk to patients. Health care professionals should consider discussing more specifically with patients the oral sex risk for transmission of HIV and other sexually transmitted diseases.

Adult↗
PubMed1994

A low dose of subcutaneous nicotine improves information processing in non-smokers.

Many studies have found that cigarette smoking or nicotine improves mental functioning in abstinent smokers. An unresolved issue is whether this improvement is due primarily to a direct facilitation of performance or to relief of the impairment caused by nicotine withdrawal. We evaluated the performance of 12 non-smokers before and twice (15 and 45 min) after a subcutaneous injection of 0.8 mg nicotine, 0.8 ml saline, and a control no treatment, on a choice reaction time (RT) task. Each treatment was given on a separate day; the control day was given on the first session. The order of nicotine and saline was balanced between subjects, and injections were given double-blind. The RT task manipulated stimulus and response processing. These manipulations consisted of two levels of stimulus complexity and two levels of response complexity, resulting in four task conditions. These manipulations along with latency measures of the event-related potential were used to identify the components of processing that mediated nicotine's effects on performance. During each active drug session blood nicotine levels, cardiovascular, and subjective responses were measured before and after each of the three tests (pre-drug, 15 min and 45 min post-drug). For the information processing measures only the comparisons of the pre- and 15-min post-test showed significant drug effects. Nicotine compared to saline significantly increased the number of responses at the fast end of the RT distribution. However, there were no changes in accuracy. Nicotine also speeded mean RT compared with saline or the control day, but the effects were only significant for the control-nicotine comparison.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Drugs and human information processing.

Human performance on a choice-reaction time task (Eriksen task) has been simulated by a neural network. In simulations, the network captures many features of normal performance. In addition, changing gain in different layers produces changes that simulate different drug-induced changes. Data from a similar choice-reaction time task have been reanalyzed to test some of the predictions derived from changing gain in different layers. Clonidine antagonizes norepinephrine and acetylcholine activities and changes speed-accuracy tradeoff (i.e., increased frequency of errors at any specified reaction time). That is predicted when gain is reduced in lower layers (attention layer and input layer) of the network. By contrast, manipulating dopamine activity (with pimozide and amphetamine) changes reaction time without changing speed-accuracy tradeoff functions. That is predicted when gain is changed in the output layer of the network.

Humans↗
PubMed1994

The effect of D-amphetamine, clonidine, and yohimbine on human information processing.

Twelve subjects were tested with D-amphetamine, yohimbine, clonidine, and a placebo on a task with two levels of stimulus and two levels of response complexity. The purpose of this study was to test the hypothesis that noradrenergic drugs affect early stimulus processes. D-amphetamine speeded reaction time (RT), clonidine slowed it, and yohimbine had no effect. D-amphetamine and yohimbine decreased N1 latency and clonidine increased it. D-amphetamine and yohimbine decreased P3 latency and clonidine increased it but, in each case, only when latency estimates were based on single trials, not on averages. D-amphetamine's effect on RT, not P3, as measured by the average, is consistent with previous results. Single trial measures appear more sensitive. Speeding of N1 and single-trial P3 data indicate that noradrenergic drugs affect processing of early (visual) information. D-amphetamine's speeding of single-trial P3 estimates was attributed to its noradrenergic actions. Yohimbine's speeding of P3 without changing RT is consistent with neural net (parallel) simulations but not with a serial model. These findings support the assumption that different neurotransmitters modulate specific cognitive processes.

Adult↗