Biomedical subjects

D Jacobs

Publications and source records attributed to D Jacobs.

At least 55 records · Page 3Linked to original sources

PubMed1997

A universal procedure for primer labelling of amplicons.

Detection and visualisation of nucleic acids is integral to genome analyses. Exponential amplification procedures have provided the means for the manipulation of nucleic acid sequences, which were otherwise inaccessible. We describe the development and application of a universal method for the labelling of any PCR product using a single end-labelled primer. Amplification was performed in a single reaction with the resulting amplicon labelled to a high specific activity. The method was adapted to a wide range of PCRs and significantly reduced the expense of such analyses.

DNA Primers↗

PubMed1997

Improved methods for in situ enzymatic amplification and detection of low copy number genes in bacteria.

We present alternative and improved protocols for in situ analysis of single copy genes in prokaryotes. Primed in situ amplification (PRINS) and cycle PRINS were used to detect, via the incorporation of a fluorescein labelled nucleotide, the presence of specific genes carried on both high and low copy number plasmids in individual cells of Escherichia coli and a marine bacterium, SW5. The optimised protocols described enabled a significant reduction in non-specific signals whilst maintaining high fluorescent activity via labelled nucleotide incorporation. In addition, nucleic acids were amplified linearly and were retained within the permeabilised microbial cells. These methods provide considerable advances in sensitivity, specificity and reliability compared to current protocols for bacterial in situ nucleic acid amplification.

Gene Dosage↗

PubMed1997

The validity of new memory complaints in the elderly.

OBJECTIVE: To determine the validity of new subjective memory complaints (MCs) from individuals who previously, when without dementia, denied having MCs. DESIGN: Prospective cohort. SETTING: Longitudinal, community-based study of aging and dementia. PATIENTS: One hundred thirty-three community-dwelling elderly individuals who were part of a registry for the study of conditions related to aging in North Manhattan, NY. Patients were selected if they were initially without dementia and had completed at least 2 successive annual clinical and neuropsychological evaluations and provided their own medical history. MAIN OUTCOME MEASURES: Performance on memory tests--the Buschke Selective Reminding Test and a visual memory task--and global performance on a neuropsychological test battery and clinical evaluation, by which questionable dementia or dementia was diagnosed according to a well-defined paradigm. RESULTS: Fifty-three subjects with MCs at the initial evaluation performed no worse on the memory test than the 80 subjects who denied MCs initially. There was a weak association between MCs and the diagnosis of questionable dementia at baseline (P = .04), but this was nonsignificant after adjusting for age and education. At 1-year follow-up, 21 of the 80 without baseline MCs now reported MCs. At the follow-up evaluation, these 21 subjects performed significantly worse on the memory tests, were 5 times more likely to have significant cognitive impairment, and had shown significantly greater decline over the preceding year on several of the cognitive measures than the 59 who continued to deny MCs. CONCLUSION: New MCs from individuals, who when without dementia recently denied MCs, may suggest the presence of significant impairment of memory or cognition.

Aged↗

PubMed1997

Whole-grain consumption and chronic disease: protective mechanisms.

Dietary guidance recommends consumption of whole grains to reduce the risk of chronic diseases including cancer and cardiovascular disease. Epidemiologic studies support the belief that whole grains are protective against cancers, especially gastrointestinal cancers such as gastric and colonic, and cardiovascular disease. Components in whole grains that may be protective are diverse and include compounds that affect the gut environment, i.e., dietary fiber, resistant starch, and other undigestible compounds in whole grains, compounds that function as antioxidants such as trace minerals and phenolic compounds, and compounds that are phytoestrogens with potential hormonal effects. Many of the protective compounds in whole grains are also in fruits and vegetables, but some plant compounds are more concentrated in whole grains, such as phenolic compounds including ferulic and caffeic acid. Other potential mechanistic effects of whole grains include binding of carcinogens and modulation of glycemic index. Clearly, the range of protective substances in whole grains is impressive, and advice to consume additional whole grains is justifiable.

Acute Disease↗

PubMed1997

Dissolution of artificial (natural) stones in a standard model: first results.

In studying the dissolution of stones in vitro, the advantage of artificial stones in comparison to natural stones is that one can get substance-specific standardized and reproducible results. Our investigations were performed with artificial stones composed of natural material (calcium apatite). These stones were of spherical form and consisted of layers built up around a core. They were comparable to natural stones in their physical properties. Litholysis was performed in a special apparatus with continuous exposure to Suby G solution under standard conditions. Natural stones of the same chemical composition served as a reference. Statistical measurements were performed. By hardening of the artificial stones, it was possible to reach a dissolution comparable to natural stones composed of calcium apatite depending on the Suby G concentration (artificial 2.5 resp. 4.75 mg/h; natural 2.18 resp. 4.2 mg/h). For the first time, an artificial stone model has been created with reproducible behaviour in response to chemolitholysis and with properties of dissolution comparable to those of natural stones of identical chemical composition.

Apatites↗

PubMed1997

rRNA sequences and evolutionary relationships among toxic and nontoxic cyanobacteria of the genus Microcystis.

A primary-structure analysis of the 16S rRNA gene was performed with 10 strains representing five described and one unidentified species of the genus Microcystis. The phylogenies determined illustrate the evolutionary affiliations among Microcystis strains, other cyanobacteria, and related plastids and bacteria. A cluster of 10 strains that included hepatotoxic isolates identified as Microcystis aeruginosa formed a monophyletic group. However, the genus Microcystis appeared to be polyphyletic and contained two strains that clustered with unicellular cyanobacteria belonging to the genus Synechococcus. The clustering of related Microcystis strains, including strains involved in the production of the cyclic peptide toxin microcystin, was consistent with cell morphology, gas vacuolation, and the low G + C contents of the genomes. The Microcystis lineage was also distinct from the lineage containing the unicellular genus Synechocystis and the filamentous, heterocyst-forming genus Nostoc. The secondary structure of a Microcystis 16S rRNA molecule was determined, and genus-specific sequence signatures were used to design primers that permitted identification of the potentially toxic cyanobacteria belonging to the genus Microcystis via DNA amplification.

Bacterial Proteins↗

PubMed1997

Evaluation of trophoblast HLA-G antigen with a specific monoclonal antibody.

A monoclonal antibody to HLA-G has been generated by immunizing HLA-A2.1/human beta 2-microglobulin (beta 2 m) double transgenic mice with murine L cells transfected with both human beta 2 m and HLA-G. This monoclonal antibody, designated as G233, has been found not to cross-react with other HLA class I antigens when tested on numerous cell lines by flow cytometry. With immunohistology, all populations of extravillous trophoblast (cell columns, interstitial trophoblast, endovascular trophoblast, placental bed giant cells) were stained. An extensive range of adult and fetal tissues was also tested but none reacted with monoclonal antibody G233, including those previously reported to express HLA-G mRNA, indicating that the protein has a highly restricted distribution. Failure to detect HLA-G in the fetal thymus raises the question as to how T-cell tolerance to this antigen is induced. Immunoprecipitation of trophoblast surface proteins with monoclonal antibody G233 revealed a heavy chain of 39 kDa and a light chain of 12 kDa, indicating that HLA-G expressed on the surface of trophoblast is complexed with beta 2 m. However, sequential immunoprecipitation with monoclonal antibody W6/32 followed by monoclonal antibody G233 continued to detect a residual band of 39 kDa, suggesting that trophoblast surface HLA-G may also occur as free heavy chains not associated with beta 2 m. Immunoprecipitation followed by two dimensional gel electrophoresis showed that monoclonal antibody G233 recognizes several isoforms of HLA-G from trophoblast similar to the characteristic spot array previously described for HLA-G. This monoclonal antibody G233 will be highly useful in future experiments to elucidate the function of HLA-G.

Adult↗

PubMed1997

In situ analysis of nucleic acids in cold-induced nonculturable Vibrio vulnificus.

Low-temperature-induced nonculturable cells of the human pathogenic bacterium Vibrio vulnificus retained significant amounts of nucleic acids for more than 5 months. Upon permeabilization of fixed cells, however, an increasing number of cold-incubated cells released the nucleic acids. This indicates substantial degradation of DNA and RNA in nonculturable cells prior to fixation. Treatment of permeabilized cells with DNase and RNase allowed differential staining of DNA and RNA with the nucleic acid dye 4',6-diamidino-2-phenylindole (DAPI). Epifluorescence microscopy revealed that the could-induced nonculturable populations of V. vulnificus are highly heterogeneous with regard to their nucleic acid content. The fraction of nonculturable cells which maintained DNA and RNA structures decreased gradually during cold incubation. After 5 months at 5 degrees C, less than 0.05% of the cells could be observed to retain DNA and RNA. In parallel with the loss of nucleic acids, an increase in the concentrations of UV-absorbing material in the culture supernatants was observed in nonculturable-cell suspensions. It is hypothesized that there are two phases of the formation of nonculturable cells of V. vulnificus: the first involves a loss of culturability with maintenance of cellular integrity and intact RNA and DNA (and thus possibly viability), and the second is typified by a gradual degradation of nucleic acids, the products of which partly remain inside the cells and partly diffuse into the extracellular space. A small number of nonculturable cells, however, retain DNA and RNA, and thus may be viable despite having reduced culturability.

Cold Temperature↗

PubMed1997

School-related issues among HIV-infected children.

OBJECTIVE: Many children with human immunodeficiency virus (HIV) infection are surviving long enough to reach school age. This study describes issues related to school attendance and disclosure of HIV infection in a population of HIV-infected children. METHODS: A statewide pediatric HIV surveillance system was used to collect data on school-age (>/=5 years old) HIV-infected children. In addition, HIV clinic nurses familiar with the child's history participated in a cross-sectional survey that collected information on school-related issues during the 1993-1994 school year. RESULTS: Of the 92 school-age children, only 3 were too ill to attend school. Another 5 children were home-schooled. Of the 84 who attended school outside the home, 25% had severe symptoms of HIV infection (Centers for Disease Control and Prevention [CDC] clinical category C). Absence from school ranged from less than 2 weeks during the year for half of the children (51%) to more than 8 weeks for 9 children (12%). Twenty-nine percent of the children received medication in school, usually administered by the school nurse. Over two thirds of the 50 children ages 5 to 10 years had not been told that they had HIV infection. Only 1 of the 20 children more than 10 years of age was not aware of her HIV infection. For 53% of the children attending school, no school personnel had been informed of the child's HIV infection. Administration of HIV medications at school, age of child, and treatment at one particular HIV clinic were associated with the parents' decision to inform school personnel. In the 47% of cases where the school had been informed, school nurses were most frequently notified, followed by principals and teachers. CONCLUSION: Only 3% of school-age children were too ill to attend school, and almost all were enrolled in public schools. The number of HIV-infected children reaching school age will continue to grow, and public schools will bear the responsibility for educating these children. Health care providers will increasingly be called upon for guidance by both educators and families to assure that HIV-infected children receive the best education possible.

Absenteeism↗

PubMed1997

Production of artificial urinary stones from natural materials and their physical properties. First results.

Considered from a clinical point of view, all artificial stones known so far are inappropriate for experimental investigations, because they do not correspond to natural urinary stones in shape, physical properties and chemical composition. A special technique has now been developed for the production of biometric artificial stone models. Standard artificial carbonate apatite stones were produced by a coating technique where several layers of a suspension consisting of pure substance were applied around a core. Density and crushing strength of these ball-shaped artificial stones corresponded to natural apatite stones. Experimental chemolitholysis investigations showed comparable results in respect to the dissolution of artificial apatite stones and of natural stones of the same chemical composition. The disintegration behaviour was studied in ESWL tests which revealed a correlation between generator voltage and number of shock waves necessary for complete disintegration. For the first time, an artificial urinary stone has now been produced which is comparable to a natural stone of the same chemical composition not only in shape but also in its physical properties and lysis behaviour. These stones are suitable for use in systemic scientific investigations on disintegration and chemolitholysis.

Apatites↗

PubMed1997

Long-term results and complications of renal transplantation: the Hennepin experience.

Approximately one sixth of patients receiving renal transplants have a functioning kidney beyond 20 years. Chronic rejection is the predominant cause of late allograft loss. Malignancy, cardiovascular disease, hepatic failure, and infections are the major causes of late death. Early detection and control of the risk factors that contribute to patient death should favorably influence the long-term success of renal transplantation.

Adult↗

PubMed1996

Effect of oestrogen during menopause on risk and age at onset of Alzheimer's disease.

BACKGROUND: Oestrogen use by postmenopausal women has many health benefits, but findings on the effect of oestrogen in Alzheimer's disease are conflicting. Oestrogen promotes the growth and survival of cholinergic neurons and could decrease cerebral amyloid deposition, both of which may delay the onset or prevent Alzheimer's disease. To investigate whether use of oestrogen during the postmenopausal period affects the risk of Alzheimer's disease, we studied 1124 elderly women who were initially free of Alzheimer's disease, Parkinson's disease, and stroke, and who were taking part in a longitudinal study of ageing and health in a New York City community. METHODS: Relative risks and age-at-onset distributions were calculated from simple and adjusted Cox proportional hazards models. Standard annual clinical assessments and criterion-based diagnoses were used in follow-up (range 1-5 years). FINDINGS: Overall, 156 (12.5%) women reported taking oestrogen after onset of menopause. The age at onset of Alzheimer's disease was significantly later in women who had taken oestrogen than in those who did not and the relative risk of the disease was significantly reduced (9/156 [5.8%] oestrogen users vs 158/968 [16.3%] nonusers; 0.40 [95% Cl 0.22-0.85], p < 0.01), even after adjustment for differences in education, ethnic origin, and apolipoprotein-E genotype. Women who had used oestrogen for longer than 1 year had a greater reduction in risk; none of 23 women who were taking oestrogen at study enrolment has developed Alzheimer's disease. INTERPRETATION: Oestrogen use in postmenopausal women may delay the onset and decrease the risk of Alzheimer's disease. Prospective studies are needed to establish the dose and duration of oestrogen required to provide this benefit and to assess its safety in elderly postmenopausal women.

Age of Onset↗

PubMed1996

Laparoscopic anatomical (hepatic) left lateral segmentectomy-technical aspects.

Laparoscopic liver surgery is a tremendous challenge. The authors report a left liver lobectomy and removal by a total laparoscopic approach. Anatomical left lateral laparoscopic segmentectomy was performed on a woman who had a symptomatic hepatic adenoma. The patient was discharged after an uncomplicated postoperative recovery; the hospital stay and convalescence period were very short. The cosmetic result was good.

Adenoma, Liver Cell↗

PubMed1996

Is deep vein thrombosis surveillance warranted in high-risk trauma patients?

BACKGROUND: Deep vein thrombosis (DVT) has been reported to occur in 20% to 40% of high-risk trauma patients if no prophylaxis is used. The purpose of this study was to determine the incidence of DVT and utility of a screening program in a high-risk group of trauma patients for whom routine DVT prophylaxis was utilized. PATIENTS AND METHODS: Of 3,154 trauma admissions over a 20-month period, 343 patients (10.9%) identified as high risk based on established criteria (prolonged bed rest, Glasgow coma score (GCS) of 7, spinal injury, lower extremity or pelvic fracture) were placed on a prospective surveillance protocol using color-flow duplex scanning and received thromboembolic prophylaxis. RESULTS: Twenty-three thromboembolic complications occurred, including 20 DVTs (5.8%) and 3 pulmonary emboli ([PE] 1%). Univariate analysis showed that the risk of DVT was related to age (52.6 + 19.9 years versus 38.1 + 18.5; P = 0.001), a longer hospital stay (31.4 versus 17.8 days; P = 0.001), or the presence of spinal fracture (12.6% versus 3.5%; P = 0.01). Discriminant function analysis revealed that length of stay, intensive care unit days, age, and GCS allowed correct classification of those who did not develop DVT in 97% of cases but was only correct in 15% of cases in predicting those who would develop DVT. Injury severity score (ISS) was not predictive in this multivariate analysis. Seventeen (85%) DVTs were unsuspected clinically. Study patients received an average of 3.5 studies at an overall charge of $313,330 to detect 17 clinically unsuspected DVTs (5%). This represents about 5% of the total bed charges for these patients, or $18,000 per DVT. CONCLUSIONS: These results suggest that standard use of DVT prophylaxis in a high-risk trauma population leads to a low incidence of DVT and that a screening protocol is effective in detecting unsuspected DVTs. Use of a surveillance protocol, however, may reduce but will not eliminate the incidence of pulmonary emboli in this patient population.

Adult↗

PubMed1996

Outcome and utility of scoring systems in the management of the mangled extremity.

BACKGROUND: The role of scoring systems as predictors of amputation and functional outcome in severe blunt extremity trauma was examined. METHODS: All severe extremity injuries treated over a 10-year period were scored retrospectively using four scoring systems: Mangled Extremity Syndrome Index (MESI), Mangled Extremity Severity Score (MESS), Predictive Salvage Index (PSI), and Limb Salvage Index (LSI). RESULTS: Twenty-three upper (UE) and 51 lower extremity (LE) injuries were evaluated. Sensitivity and specificity, respectively, were MESI 100% and 50%, MESS 79% and 83%, PSI 96% and 50%, and LSI 83% and 83%. For each system, there were no differences between patients with good and poor functional outcomes. CONCLUSION: All of the scoring systems were able to identify the majority of patients who required amputation. However, prediction in individual patients was problematic. None of the scoring systems were able to predict functional outcome.

Adult↗

PubMed1996

On combining protein sequences and nucleic acid sequences in phylogenetic analysis: the homeobox protein case.

Amino acid encoding genes contain character state information that may be useful for phylogenetic analysis on at least two levels. The nucleotide sequence and the translated amino acid sequences have both been employed separately as character states for cladistic studies of various taxa, including studies of the genealogy of genes in multigene families. In essence, amino acid sequences and nucleic acid sequences are two different ways of character coding the information in a gene. Silent positions in the nucleotide sequence (first or third positions in codons that can accrue change without changing the identity of the amino acid that the triplet codes for) may accrue change relatively rapidly and become saturated, losing the pattern of historical divergence. On the other hand, non-silent nucleotide alterations and their accompanying amino acid changes may evolve too slowly to reveal relationships among closely related taxa. In general, the dynamics of sequence change in silent and non-silent positions in protein coding genes result in homoplasy and lack of resolution, respectively. We suggest that the combination of nucleic acid and the translated amino acid coded character states into the same data matrix for phylogenetic analysis addresses some of the problems caused by the rapid change of silent nucleotide positions and overall slow rate of change of non-silent nucleotide positions and slowly changing amino acid positions. One major theoretical problem with this approach is the apparent non-independence of the two sources of characters. However, there are at least three possible outcomes when comparing protein coding nucleic acid sequences with their translated amino acids in a phylogenetic context on a codon by codon basis. First, the two character sets for a codon may be entirely congruent with respect to the information they convey about the relationships of a certain set of taxa. Second, one character set may display no information concerning a phylogenetic hypothesis while the other character set may impact information to a hypothesis. These two possibilities are cases of non-independence, however, we argue that congruence in such cases can be thought of as increasing the weight of the particular phylogenetic hypothesis that is supported by those characters. In the third case, the two sources of character information for a particular codon may be entirely incongruent with respect to phylogenetic hypotheses concerning the taxa examined. In this last case the two character sets are independent in that information from neither can predict the character states of the other. Examples of these possibilities are discussed and the general applicability of combining these two sources of information for protein coding genes is presented using sequences from the homeobox region of 46 homeobox genes from Drosophila melanogaster to develop a hypothesis of genealogical relationship of these genes in this large multigene family.

Algorithms↗

PubMed1995

The concentration of cellular nitrogenase proteins in Azotobacter vinelandii whole cells as determined by activity measurements and electron paramagnetic resonance spectroscopy.

The concentration of MoFe protein (Av1) in Azotobacter vinelandii whole-cell crude extract was measured by electron paramagnetic resonance spectroscopy at g = 3.7 resonance. The Av1 concentration was also measured from the activity of crude extract to which increasing amounts of purified Av1 and Av2 were added. The Av2 concentration was determined by fitting activity measurements of crude extract and crude extract to which purified Av2 was added. The Av1 concentration was found to be 26-28 microM and that for Av2 was 42-45 microM in whole cells, with a Av2/Av1 ratio of 1.6. In vitro activity measurements carried out as a function of Av1 concentration at Av2/Av1 ratios of 1 and 4 showed a dilution effect below 0.08 microM, a factor of 2 below that observed for nitrogenase reactivity for Klebsiella pneumoniae. No deviations from linearity were observed up to 26 microM for the Av1-Av2 interaction. The flavoprotein (AvFlp) was shown to enhance nitrogenase reactivity at low Av2/Av1 ratios, a result attributed to decreasing the Km for Av2-Av1 interaction. Direct reduction of bound Av2 is possibly the source of this kinetic enhancement. The kinetic results are considered in terms of the Thorneley and Lowe scheme.

Azotobacter vinelandii↗

PubMed1995

National Medical Association Surgical Section position paper on violence prevention. A resolution of trauma surgeons caring for victims of violence.

The epidemic of intentional injury continues to be a leading cause of premature death in America. The ravages of violence are particularly devastating within the minority community. With this position paper from the Surgical Section of the National Medical Association (the country's oldest and largest organization of minority physicians), a group of trauma surgeons and surgical intensivists resolve to focus on underused violence prevention opportunities and to extend their spheres of influence beyond the walls of their institutions and emphasize violence prevention activities.

Humans↗