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Biomedical subjects

D A Klein

Publications and source records attributed to D A Klein.

At least 19 recordsLinked to original sources
PubMed2006

Intake, sweetness and liking during modified sham feeding of sucrose solutions.

Although sweet solids and liquids are palatable to humans and ingested frequently when readily available, the quantitative relationship between sweet taste and intake has not been reported in humans. To investigate the quantitative relationship between sweet taste and intake directly, we adapted the modified sham feeding technique, previously used in humans for the study of the orosensory control of autonomic, neuroendocrine, and metabolic mechanisms, to measure the intake of solutions both unsweetened and sweetened with four concentrations of sucrose. By limiting the sucrose stimuli to the mouth, the modified sham feeding technique measures the orosensory stimulation of intake by sucrose in the absence of inhibitory postingestive stimulation. Nine healthy women were randomly presented with two series of five solutions of cherry Kool Aid unsweetened or sweetened with one of four concentrations of sucrose (2.5%, 5%, 10%, or 20%) in a closed opaque container fitted with a straw. They were instructed to sip as much as they wanted of the liquid during 2-min trials and to spit the fluid out into another opaque container. At the end of each trial, they used Visual Analogue Scales to rate the perceived intensities of sweetness and liking of the liquid that they had just sipped and spit. Intake, liking and perceived sweetness were significantly affected by sucrose concentration (p values</=0.038). Intake at 20% was not significantly larger than 10% or 5%. The effects of sucrose were presumably due to orosensory stimulation in the absence of postingestive stimulation because the amount of liquid spit out did not differ significantly from the amount sipped.

Adult↗
PubMed2004

Filamentous fungi: the indeterminate lifestyle and microbial ecology.

The filamentous fungi have dynamic and variable hyphal structures within which cytoplasm can be moved, synthesized, and degraded, in response to changes in environmental conditions, resource availability, and resource distribution. Their study has gone through several phases. In the first phase, direct observation was emphasized without undue concern for interior structures or in the presence of cytoplasm. By the mid-1970s, single biochemical proxies (ergosterol, marker fatty acids, chitin derivatives, etc.) were being used increasingly. The use of these surrogate single measurements continues, in spite of their inability to provide information on the physical structure of the filamentous fungi. Molecular approaches also are being used, primarily through the use of bulk nucleic acid extraction and cloning. Because the sources of the nucleic acids used in such studies usually are not known, taxonomic and phylogenetic information derived by this approach cannot be linked to specific fungal structures. Recently, a greater emphasis has been placed on assessing physical aspects of indeterminate fungal growth, involving the assessment of cytoplasm-filled and evacuated (empty) hyphae. Both of these parameters are important for describing filamentous fungal growth and function. The use of phase contrast microscopy and varied general stains, as well as fluorogenic substrates with observation by epifluorescence microscopy, has made it possible to provide estimates of cytoplasm-filled hyphal lengths. Using this approach, it has been possible to evaluate the responses of the indeterminate fungal community to changes in environmental conditions, including soil management. It is now possible to obtain molecular information from individual bacteria and fungal structures (hyphae, spores, fruiting bodies) recovered from environments, making it possible to link individual fungal structures with their taxonomic and phylogenetic information. In addition, this information can be considered in the context of the indeterminate filamentous fungal lifestyle, involving the dynamics of resource allocation to hyphal structural development and synthesis of cytoplasm. Use of this approach should make it possible to gain a greater appreciation of the indeterminate filamentous fungal lifestyle, particularly in the context of microbial ecology.

Cytoplasm↗
PubMed2003

Eating disorders.

Eating disorders rank among the most debilitating psychiatric disturbances that affect young women. Knowledge has increased in recent years about the two major eating disorders, anorexia nervosa (AN) and bulimia nervosa (BN); however, much remains unknown. This review article will provide an overview of the epidemiology, proposed risk factors and clinical features of AN, and BN, as well as current recommendations for evaluation and treatment of these disorders.

Adult↗
PubMed2001

Blood-retinal barrier breakdown in experimental coronavirus retinopathy: association with viral antigen, inflammation, and VEGF in sensitive and resistant strains.

Intraocular coronavirus inoculation results in a biphasic retinal disease in susceptible mice (BALB/c) characterized by an acute inflammatory response, followed by retinal degeneration associated with autoimmune reactivity. Resistant mice (CD-1), when similarly inoculated, only develop the early phase of the disease. Blood-retinal barrier (BRB) breakdown occurs in the early phase in both strains, coincident with the onset of inflammation. As the inflammation subsides, the extent of retinal vascular leakage is decreased, indicating that BRB breakdown in experimental coronavirus retinopathy (ECOR) is primarily due to inflammation rather than to retinal cell destruction. Vascular endothelial growth factor (VEGF) is upregulated only in susceptible mice during the secondary (retinal degeneration) phase.

Animals↗
PubMed2001

Vascular endothelial growth factor (VEGF), transforming growth factor-beta (TGFbeta), and interleukin-6 (IL-6) in experimental herpesvirus retinopathy: association with inflammation and viral infection.

Experimental herpesvirus retinopathy presents a unique model of a transient inflammatory response in the virus-injected eye and subsequent acute retinal necrosis and chronic inflammation in the contralateral eye. For 6 days after infection, VEGF, TGFbeta1, and TGFbeta2 were associated only with inflammatory cells in the injected eye. By 6 days (after viral antigens were no longer detected), VEGF and TGFbeta2 were upregulated in retinas of injected eyes until 8-10 days. In contralateral eyes, VEGF was first demonstrated in the retina at 6-7 days (prior to the appearance of viral antigens) and TGFbeta2 at 7-8 days. Staining for these factors was also evident around areas of necrosis. The VEGF receptor, flt-1, was associated with ganglion cells and the inner nuclear layer of normal and experimental mice and it was also demonstrated around areas of necrosis. Another VEGF receptor, flk-1, was localized to Muller cell processes and the outer plexiform layer in normal and experimental mice. Coincident with VEGF upregulation in the retinas of herpesvirus-1 injected mice, there was increased flk-1 in ganglion cells and the inner and outer nuclear layers. IL-6 was associated with Muller cell endfeet in normal mice. Following unilateral intraocular inoculation, IL-6 spread along the MUller cell processes and some astrocytes demonstrated IL-6 in both eyes at 6-8 days. The present study demonstrates that intraocular inoculation of herpesvirus is sufficient to induce VEGF, flk-1, TGFbeta2, and IL-6 in the retinas of injected and contralateral eyes. Further investigation of common signaling pathways for these factors during responses to viral infection and the development of acute retinal necrosis could provide information useful for therapeutic intervention in human herpesvirus retinopathy.

Animals↗
PubMed2000

Heteroduplex resolution using T7 endonuclease I in microbial community analyses.

Microbial community analyses using molecular techniques, such as PCR followed by genomic library construction, have been helpful in better understanding microbial communities. This is especially critical in ecological systems where most of the microbes present cannot be cultured using traditional techniques. Unfortunately, there are problems associated with the use of such molecular techniques for the analysis of microbial community structure, primarily from the frequent formation of PCR artifacts. Multitemplate PCR is often subject to errors such as heteroduplex formation that is generated during the amplification of a particular gene from a mixed community of DNA. Based on work in this laboratory, heteroduplexes may be resolved before carrying out genomic library construction by including a digestion step with T7 endonuclease I. Here, the 18S rDNA gene of fungi was amplified from soil community DNA and digested with T7 endonuclease I to resolve any heteroduplexes present in the PCR product before cloning. These samples were compared with replicates that did not receive the T7 endonuclease I treatment. Digestion of the amplified community 18S rDNA with 10 U T7 endonuclease I/microgram DNA prior to cloning eliminated heteroduplexes, leaving only the desired clones. Without the T7 endonuclease I treatment, heteroduplexes were produced in approximately 10% of the recombinants screened. The addition of this step may eliminate heteroduplexes from PCR products and ensure that subsequent genomic library construction is not compromised.

Artifacts↗
PubMed1999

Wandering behaviour in community-residing persons with dementia.

OBJECTIVES: To examine wandering behaviour in elderly demented persons in the community setting with respect to dementia characteristics and other factors that might influence wandering behaviour; to generate a statistical model to assess the relative importance of these various factors in predicting wandering behaviour. DESIGN: Cross-sectional, case-control investigation. SETTING: University-affiliated outpatient neuropsychiatric assessment center. PARTICIPANTS: Six hundred and thirty-eight consecutive community-residing new patients with dementia referred for evaluation. MEASUREMENTS: Comprehensive neuropsychiatric evaluation, including rating with Mini-Mental State Examination; General Medical Health Rating; Comell Scale of Depression in Dementia and caregiver interview. RESULTS: Wandering behaviour occurred in 17.4% of participants. It was significantly more prevalent in patients with Alzheimer Dementia (AD), patients with dementia of longer duration, and patients with more severe dementia. Wandering behaviour was associated with moderate to severe depression, delusions, hallucinations, and sleep disorder. Other significant associations of wandering behaviour included use of neuroleptic medication and male gender. After statistical adjustment for other variables, duration of dementia, severity of dementia and presence of sleep disorder retained significant statistical association with wandering behaviour. CONCLUSIONS: Wandering behaviour among community-residing elderly dementia patients is associated with a number of factors, some of which may be subject to modification. It is possible that management of coexistent psychopathology, particularly of sleep disorder, and of the underlying disease process of AD would help to ameliorate this problematic behavioural disorder. Further investigation is warranted into the relationship between neuroleptic medication and wandering behaviour and into possible alternative measures to control agitation in elderly dementia patients.

Age Distribution↗
PubMed1998

Increased vascular endothelial growth factor (VEGF) and transforming growth factor beta (TGFbeta) in experimental autoimmune uveoretinitis: upregulation of VEGF without neovascularization.

Experimental autoimmune uveoretinitis (EAU) was induced in Lewis rats and B10.A mice by immunization with S-antigen (S-Ag) to study the potential roles of vascular endothelial growth factor (VEGF) and the beta1 and beta2 isoforms of transforming growth factor (TGFbeta1 and TGFbeta2) during the progression of the disease. VEGF has been implicated as an angiogenic factor in ischemic retinopathies; however, Lewis rats developing EAU have high levels of VEGF in the retina, but no neovascularization. In the present study, immunohistochemical staining for VEGF, TGFbeta1 and TGFbeta2 was performed on the retinas of Lewis rats developing EAU or with oxygen-induced ischemic retinopathy. In rats immunized with S-antigen, a marked upregulation of VEGF was immunohistochemically visualized from the inner nuclear layer to the inner limiting membrane prior to blood-retinal barrier (BRB) failure and lymphocytic infiltration. VEGF is normally induced by hypoxia and its induction leads to neovascularization. Coincident with the increase in VEGF, there was increased immunoreactivity for TGFbeta1 and TGFbeta2 within the same layers of the retina. In contrast, rats with ischemic retinopathy and retinal neovascularization showed only a modest increase in VEGF immunoreactivity, which is largely confined to retinal ganglion cells and inner retinal vessels, and little or no increase in TGFbeta1 or TGFbeta2. In addition, in mice developing EAU, which does not have an abrupt onset as it does in rats and may involve neovascularization, a comparable upregulation of VEGF in the inner retina to that seen in rats developing EAU occurs with no increase in TGFbeta1 or TGFbeta2. Since TGFbeta can inhibit endothelial cell proliferation, it is likely that an increase in TGFbeta may prevent VEGF from exerting its endothelial growth activity in the rat EAU model, but VEGF may be operative in inducing BRB failure. These data suggest that there is a complex interaction among growth factors in the retina and that retinal neovascularization may require an imbalance between stimulatory and inhibitory factors.

Animals↗
PubMed1998

Detection of Cyclospora cayetanensis in wastewater.

Cyclospora cayetanensis causes diarrheal disease worldwide without a confirmed mode of transmission. Wastewater was examined for the presence of this organism. Oocysts were detected microscopically, and their identity was confirmed by molecular techniques. These findings verify that current techniques can isolate Cyclospora oocysts and suggest that fecally contaminated water may act as a vehicle of transmission.

Animals↗
PubMed1997

Residue-based control of helix shape in beta-peptide oligomers.

Proteins and RNA are unique among known polymers in their ability to adopt compact and well-defined folding patterns. These two biopolymers can perform complex chemical operations such as catalysis and highly selective recognition, and these functions are linked to folding in that the creation of an active site requires proper juxtaposition of reactive groups. So the development of new types of polymeric backbones with well-defined and predictable folding propensities ('foldamers') might lead to molecules with useful functions. The first step in foldamer development is to identify synthetic oligomers with specific secondary structural preferences. Whereas alpha-amino acids can adopt the well-known alpha-helical motif of proteins, it was shown recently that beta-peptides constructed from carefully chosen beta-amino acids can adopt a different, stable helical conformation defined by interwoven 14-membered-ring hydrogen bonds (a 14-helix; Fig. 1a). Here we report that beta-amino acids can also be used to design beta-peptides with a very different secondary structure, a 12-helix (Fig. 1a). This demonstrates that by altering the nature of beta-peptide residues, one can exert rational control over the secondary structure.

Amino Acids↗
PubMed1997

Making effective referrals: a knowledge-management approach.

Patients and physicians often choose specially consultants with only limited knowledge of the available options. Access to information about specialists that was directly relevant to patient and clinician preferences could improve the effectiveness of the referral process. We have developed a prescriptive representation of the process of selecting consultants. This "referral map," based on decision theory, uses patient and provider preferences elicited through a literature review and interviews with physicians and provides a formal framework for representing referral knowledge and for evaluating referral options. Our method suggests that the goals and processes of selecting consultants can be managed more systematically using explicit repositories. Such systematic management promises to have a beneficial impact on the delivery of health care, as well as on patient satisfaction.

Decision Support Techniques↗
PubMed1996

Development of an affordable hi-resolution activity monitor system for laboratory animals.

We describe a hardware and software system for recording and analyzing the spatial and temporal pattern of locomotor activity of laboratory animals. The system offers maximal spatial resolution 500-fold greater than existing light beam monitors. An infrared motion analysis systems (MacReflex, Qualysis) simultaneously tracks the location of up to 20 subjects (identified by reflective markers) to within 0.04 mm at a rate of up to 50 Hz. Macintosh software provides measures of distance traveled, amount of area traversed, number of position changes (microevents), average time between movements, number of left and right turns, number of forward movements and reversals, as well as temporal and spatial scaling exponents. This system was validated by comparing these parameters to direct observer scoring of video tapes and other commercially available activity monitors. Our findings show that applying reflective markers to the subjects does not significantly alter activity levels. The effect of pharmacological manipulation with d-amphetamine is provided to show the value of the different activity parameters. The main advantages of this system are very high spatial resolution, capacity to monitoring up to 20 animals simultaneously at reasonable cost, and lack of sensitivity of the system to ambient lighting. The main limitation is the need to apply reflective markers.

Animals↗
PubMed1996

The attitudes of medical inpatients toward psychiatric consultation: a re-examination.

OBJECTIVE: Several surveys from twenty to thirty years ago demonstrated that approximately 80 percent of patients were readily accepting of psychiatric consultation. The aim of this study was to re-examine whether medical inpatient attitudes toward psychiatric consultation have changed in the past twenty-five years and whether the type of psychiatric disorder affects the attitude toward consultation. METHOD: Forty-eight medical inpatients seen in psychiatric consultation consented to answering a questionnaire pre- and post-consultation to assess their attitudes to this intervention. Chi-square and t-tests were used to determine statistically significant differences between the "before" and "after" consultation groups. RESULTS: Eight-one percent stated they would be moderately, to very, agreeable to psychiatric consultation if their primary care doctor felt it was indicted. Sixty-seven percent claimed not to have been informed beforehand that a psychiatric consultation was requested. Only 8 percent of patients were disinterested in having the consultation. Psychiatric diagnosis (primary vs. organic) and the attitude toward psychiatric consultation were not significantly related. CONCLUSIONS: Our results show little change in attitude over the past twenty-five years and support earlier studies that show medical inpatients are generally accepting of psychiatric consultation, that consultation does not pose a threat to the doctor-patient relationship, and that careful preparation of the patient by the primary care provider can improve patients' attitudes toward the consultation.

Adult↗
PubMed1995

Development of an animal model of fluoxetine akathisia.

1. Akathisia describes the pattern of intense inner restlessness often associated with neuroleptic and antidepressant treatment. 2. The authors postulated that drug-induced akathisia would be characterized by more position changes and less time spent immobile, in the absence of significant increase in ambulation. In contrast, a psychomotor stimulant would produce both activation and ambulation. 3. Procedures and instruments were developed to test this hypothesis. Adult rats were habituated for 72 hours to the testing environment, and their precise pattern of movements was tracked and recorded (10 reading per second; resolution 0.04 mm) by an infrared motion analysis system. Activity was recorded for a 90 min period after a single injection of sub-stereotypic doses of d-amphetamine (0, 0.3, 1.0 mg/kg) or racemic fluoxetine (0, 3.0, 10.0, 20.0, or 30.0 mg/kg, s.c.). 4. Amphetamine produced both activation and ambulation. Activation was indicated by a decrease in time spent immobile, and an increase in the temporal scaling exponent, which reflects the degree the animal is "acting' in its environment, and the number of position changes. Enhanced locomotion was inferred from marked increases in both the total distance traversed and the ratio of forward movements-to-reversals and a decrease in the spatial scaling exponent, indicative of a less complex and more linear movement pattern. 5. Fluoxetine caused animals to spend more time active, but exerted little effect on locomotion. Activation was indicated by a decrease in time spent immobile and an increase in the temporal scaling exponent and number of position changes. Fluoxetine failed to significantly effect either the ratio of forward movements-to-reversals or the spatial scaling exponent. 6. These findings provide an operational definition and methodology that can be used to differentiate between psychostimulant effects and akathisic effects. This approach may have utility for screening drugs for akathisic potential, for exploring underlying mechanisms, and for developing novel treatments.

Akathisia, Drug-Induced↗
PubMed1993

Organization and nucleotide sequence of the Bacillus subtilis diaminopimelate operon, a cluster of genes encoding the first three enzymes of diaminopimelate synthesis and dipicolinate synthase.

The nucleotide sequence of a 7-kilobase segment of the Bacillus subtilis chromosome containing the entire coding regions for the enzymes catalyzing the first three steps of diaminopimelate synthesis as well as dipicolinate synthase has been determined. This group of functionally related genes, termed the dap operon, were arranged in the order orfY, orfX, asd, dapG, and dapA and were bracketed by potential rho-independent transcription terminators. The asd locus could complement the growth defect of Escherichia coli strains with an asd deletion. Disruption of the dapG locus led to the loss of aspartokinase I, with a phenotype similar to that of the temperature-sensitive dapG mutants described earlier (Roten, C. A. H., Brandt, C., and Karamata, D. (1991) J. Gen. Microbiol. 137, 951-962). The amino acid sequences of the deduced products of the asd, dapG, and dapA loci had high degrees of similarity with those of other aspartate semialdehyde dehydrogenases, aspartokinases, and dihydrodipicolinate synthases, respectively. Disruption of orfX had no effect on growth but caused a sporulation defect, characterized by low sporulation frequencies and heat-sensitive spores, which could be cured by supplementation with dipicolinate, similar to the phenotype of mutants defective in spoVF, the putative structural gene for dipicolinate synthase. Two other open reading frames, upstream of spoVF, encoded the 380 COOH-terminal residues of a protein homologous to mitochondrial processing proteases and an 85-residue polypeptide of unknown function. Transcription initiation sites associated with the orfY-orfX-asd-dapG-dapA gene cluster were mapped by primer extension. The results indicate that during vegetative growth, the three distal genes of the dap operon, asd, dapG, and dapA, are transcribed as a unit and orfY and orfX are not expressed, whereas at stage 5 of sporulation two separate transcripts are produced, one comprising all five genes, the other just the three distal genes of the operon.

Amino Acid Sequence↗
PubMed1986

Bacterial physiological diversity in the rhizosphere of range plants in response to retorted shale stress.

Bacterial populations were isolated from the soil-root interface and root-free regions of Agropyron smithii Rydb. and Atriplex canescens (Pursh) Nutt. grown in soil, retorted shale, or soil over shale. Bacteria isolated from retorted shale exhibited a wider range of tolerance to alkalinity and salinity and decreased growth on amino acid substrates compared with bacteria from soil and soil-over-shale environments. Exoenzyme production was only slightly affected by growth medium treatment. Viable bacterial populations were higher in the rhizosphere and rhizoplane of plants grown in retorted shale than in plants grown in soil or soil over shale. In addition, a greater number of physiological groups of rhizosphere bacteria was observed in retorted shale compared with soil alone. Two patterns of community similarity were observed in comparisons of bacteria from soil over shale with those from soil and retorted-shale environments. Root-associated populations from soil over shale had a higher proportion of physiological groups in common with those from the soil control than with those from the retorted-shale treatment. However, in non-rhizosphere populations, bacterial groups from soil over shale more closely resembled the physiological groups from retorted shale.

Journal Article↗