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Biomedical subjects

L Hill

Publications and source records attributed to L Hill.

At least 37 records · Page 2Linked to original sources
PubMed2000

Riverine inputs of major ions and trace elements to the tidal reaches of the River Tweed, UK.

This paper examines spatial and temporal variability in freshwater inputs of trace elements and major ions to the tidal reaches of the River Tweed. The relationships between concentrations of major ions and trace elements (in dissolved and acid-available particulate forms) and flow are examined, and a simple two-component endmember mixing analysis performed to link river water chemistry to catchment sources, and to identify whether within-river processes modify concentrations to produce non-conservative behaviour. The results indicate that most dissolved major ions and trace elements behave conservatively in the lower reaches of the River Tweed, the variability in concentrations being dominated by hydrology and the existence of different high-flow and low-flow endmember runoff chemistries. This suggests that the variability in concentration of most dissolved trace elements and major ions in the lower Tweed can be modelled using simple mixing relationships. However, the relationships between pH, Ca, Mg and Gran alkalinity show pronounced non-conservative behaviour, indicating the importance of understanding within-river process for modelling these determinants. The non-conservative behaviour identified is related to biological controls and the resultant diurnal variations in pH which promote daytime removal of Ca from solution by precipitation of calcium carbonate (and corresponding removal of Mg by co-precipitation) during extreme low-flow conditions and algal blooms during the summer.

Eutrophication↗
PubMed2000

The water quality of the River Trent: from the lower non-tidal reaches to the freshwater tidal zone

The water quality of a major river system, the River Trent, which flows into the Humber estuary and drains large centres of population and industry in central England, is examined in terms of trace element, nutrient, major-ion, suspended sediment and carbon concentrations and set within the context of the transition from non-tidal to the tidal freshwater reaches. Detailed investigation of the water quality variability in the non-tidal river Trent has revealed mainly simple patterns in dissolved chemical concentrations, controlled largely by hydrology and the mixing of baseflow and stormflow endmember chemistries. However, silicon, carbon and nitrate show much more complex behaviour, as concentrations of these chemical determinands are regulated by in-stream biological processes. Major increases in concentrations of suspended solids and acid-available particulate (AAP) trace elements are shown to be linked to tidal mobilization of sediment and the location of the 'turbidity maximum'. Reductions in the concentrations of AAP trace elements per gram of suspended sediment suggest the mobilization of a different sediment type with a lower trace element content, which may result from: (i) a secondary sediment source; or (ii) mobilization of coarser-grained sediment under the stronger tidal hydrodynamic forces. Increased correlations for AAP-trace element interrelationships downstream suggest increasing simplicity of mixing relationships.

Journal Article↗
PubMed2000

Occupational needlestick injuries in a metropolitan police force.

OBJECTIVES: Police officers are at risk of bloodborne diseases through needlestick injuries but few studies have addressed this problem. The purpose of this study was to assess the risk of needlestick injuries in law enforcement officers and to determine predictors of injuries and reporting rates. DESIGN: An anonymous, voluntary questionnaire was distributed to 1738 active-duty, metropolitan police officers. The survey included the number of needlestick injuries ever experienced, how often these were reported, activities at the time of injury and attitudes toward injuries. RESULTS: Of the 803 respondents (46.2% of survey population), 29.7% had at least one needlestick injury, and 27.7% of this group had two or more. Risk factors included evening shifts, pat-down searches, patrol duties, male gender and less experience. Only 39.2% sought medical attention for these injuries. CONCLUSIONS: Needlestick injuries occur with considerable frequency in this group of law enforcement personnel, suggesting an increased risk of becoming infected with bloodborne pathogens, including hepatitis B, hepatitis C and HIV.

Adult↗
PubMed2000

Obstetrician-gynecologists' opinions and attitudes on the role of genetics in women's health.

Our objective was to describe gynecologists' current practice patterns and opinions on genetic screening and their perceived importance of genetic screening within individual practices. A questionnaire survey was sent to 1248 American College of Obstetrics and Gynecology (ACOG) Fellows, of whom 564 (45%) responded. Results from the 428 respondents providing genetic screening for heritable diseases or disorders are reported. Forty-four percent of respondents believe advances in the treatment of genetic diseases are likely in the next 10 years. Currently, however, genetics in gynecological practice receives infrequent attention. Twenty-four percent of respondents do not routinely review family histories at gynecological visits, 39% rate genetic issues as last among priorities in the office, and only 14% obtain consent for the DNA tests that they initiate. Although 21.3% identified themselves as sole providers of genetic information and counseling to their patients, most (65.4%) note they are not confident of their knowledge of genetics, particularly concerning breast and ovarian cancer. For obstetrician-gynecologists to keep pace with the rapid changes in genetics, further education and assimilation of genetics into the routine office practice will need to occur. Not currently viewed as a priority among practitioners, issues of genetic knowledge, ethics, and test interpretation will soon need attention. National organizations, continuing medical education, and existing genetic centers will need to meet these recognized demands.

Adult↗
PubMed2000

Effects of transportation and delay in processing on the stability of nutritional and metabolic biomarkers.

The effects of transportation and delay in processing of blood samples on the concentration of biomarkers are significant in epidemiological studies for which specimens are collected from participants at locations other than a designated center or laboratory. These sources of variability in measurement were studied by collecting two sets of blood samples from 51 men between 26 and 50 years of age. The first set was sent immediately to the laboratory for processing. The second set was transported by car for one hour and then returned to the laboratory for processing. Both sets were stored together at -80 degrees C until the end of the study. Several blood constituents were evaluated. Vitamins, liver enzymes, and electrolytes showed no changes in concentration after transport by car for one hour. There were decreases in the concentrations of red and white blood cells, high-density-lipoprotein cholesterol, glucose, and creatinine after transportation. The transported total cholesterol, total testosterone, free testosterone, alkaline phosphatase, total bilirubin, and thiobarbituric acid-reactive substances increased in concentration. Although transportation and delay in processing of blood samples do not appear to greatly impact relative risk estimates, epidemiologists should be aware of these potential sources of variability in measurement and consider the consequences in their particular study.

Adult↗
PubMed2000

Why and how to measure urinary sex steroid metabolites in epidemiological studies in women.

BACKGROUND AND AIM: Although numerous investigations have evaluated the association between urinary hormone levels and chronic diseases such as breast cancer and coronary heart disease, there are few data about the reliability of urinary measurements, particularly among premenopausal women. METHODS AND RESULTS: Over a six-month period, levels of estrone-3-glucuronide and pregnandiol-3-glucuronide were measured in both morning spot and overnight urine samples from seven healthy premenopausal women (ages 33-46). During this period, each subject provided one morning spot urine sample and one overnight urine sample per menstrual cycle on the same day of her menstrual cycle. All these samples were taken out of the freezer simultaneously and sent in the same parcel on dry ice to the laboratory for hormone determinations. All samples from each person were assayed simultaneously in the same run and by the same laboratory technician in a blind fashion. The intraclass correlation coefficients (ICC) for estrone-3-glucuronide and pregnandiol-3-glucuronide for the morning spot and overnight urine samples were 0.78 and 0.46 and 0.75 and 0.64 respectively. CONCLUSIONS: These data suggest that morning spot urine determinations are reliable and constitute an efficient alternative to the more complex overnight urine collection for epidemiological evaluation of urinary hormonal profiles.

Adult↗
PubMed1999

DNA pooling and dense marker maps: a systematic search for genes for cognitive ability.

Pooling DNA from subjects within a group and comparing the pooled DNA across groups for a dense map of DNA markers offers a solution to the conundrum that linkage is systematic but not powerful whereas allelic association is powerful but not systematic. We used DNA pooling to screen 66 markers on chromosome 22 in original and replication samples of children of high general cognitive ability (g) and controls of average g. Although none of these markers survived our three-stage screening design (original pooling, replication pooling, individual genotyping), the results of DNA pooling were largely confirmed by individual genotyping. We can therefore exclude associations of major effect size on chromosome 22 for g, a key variable for cognitive neuroscience research on learning and memory.

Alleles↗
PubMed1999

Effect of tramadol and morphine on pain and gastrointestinal motor function in patients with chronic pancreatitis.

Tramadol and morphine were compared for treatment of severe chronic pancreatitis pain and their interaction with gut motor function. Oral tramadol or morphine doses were titrated double-blinded and randomized for five days in 25 patients and pain, side effects, bowel function, orocecal and colonic transit, anal resting pressure, and rectal distension thresholds were measured. Pain intensities (mean+/-SD, 0 = none, 100 = unbearable) before treatment and on day 4 were 75+/-19 and 8+/-13 with tramadol (P < 0.001), and 65+/-21 and 5+/-6 with morphine (P < 0.001). On day 4, 67% of patients with tramadol and 20% with morphine rated their analgesia as excellent (P < 0.001) with mean respective doses of 840 mg (range: 80-1920) and 238 mg (20-1125). Orocecal transit was unchanged after five days of tramadol, but increased with morphine (P < 0.05). More patients had prolonged colonic transit times with morphine by day 5 (P < 0.05). Rectal distension threshold pressures increased only with tramadol (P < 0.01). It is concluded tramadol and morphine are potent analgesics in severe chronic pancreatitis pain when individually titrated. Tramadol interfered significantly less with gastrointestinal function and was more often rated as an excellent analgesic than morphine.

Adult↗
PubMed1999

Trisomy 10: first-trimester features on ultrasound, fetoscopy and postmortem of a case associated with increased nuchal translucency.

We report a case of the prenatal diagnosis of trisomy 10 in a fetus presenting with an increased nuchal translucency thickness (5 mm) on a routine first-trimester anomaly scan at 12 weeks' gestation. Multiple abnormalities were diagnosed by ultrasound and fetoscopy. Karyotyping on chorionic villus sampling led to the diagnosis of homogeneous trisomy 10 which was confirmed by in situ hybridization on fetal tissue samples. Postmortem examination confirmed major anatomical malformations, including facial cleft, arthrogryposis of the upper and lower limbs and bilateral diaphragmatic hernia, and also revealed hypoplastic lungs, right renal agenesis and a complex cardiac malformation. Trisomy 10 is an uncommon chromosomal abnormality that is likely to be associated with increased fetal nuchal translucency. This case also emphasizes the value of a detailed anomaly scan in high-risk patients in the first trimester of pregnancy.

Abnormalities, Multiple↗
PubMed1999

DNA pooling identifies QTLs on chromosome 4 for general cognitive ability in children.

General cognitive ability (g), which is related to many aspects of brain functioning, is one of the most heritable traits in neuroscience. Similarly to other heritable quantitatively distributed traits, genetic influence on g is likely to be due to the combined action of many genes of small effect [quantitative trait loci (QTLs)], perhaps several on each chromosome. We used DNA pooling for the first time to search a chromosome systematically with a dense map of DNA markers for allelic associations with g. We screened 147 markers on chromosome 4 such that 85% of the chromosome were estimated to be within 1 cM of a marker. Comparing pooled DNA from 51 children of high g and from 51 controls of average g, 11 significant QTL associations emerged. The association with three of these 11 markers ( D4S2943, MSX1 and D4S1607 ) replicated using DNA pooling in independent samples of 50 children of extremely high g and 50 controls. Furthermore, all three associations were confirmed when each individual was genotyped separately ( D4S2943, P = 0. 00045; MSX1, P = 0.011; D4S1607, P = 0.019). Identifying specific genes responsible for such QTL associations will open new windows in cognitive neuroscience through which to observe pathways between genes and learning and memory.

Adolescent↗
PubMed1999

Effects of morphine and tramadol on somatic and visceral sensory function and gastrointestinal motility after abdominal surgery.

BACKGROUND: Chronic nociceptive input induces sensitization and changes in regulatory reflexes in animal models. In humans, postoperative somatic and visceral sensitization and the secondary effects on reflex gut motility are unclear. METHODS: Somatic and visceral sensation and gastrointestinal motility were evaluated after abdominal hysterectomies in 50 patients who were randomized to receive double-blinded postoperative 48-h infusions of morphine or tramadol. Pain scores, rectal distension, skin electric sensation and pain tolerance thresholds, and gastrointestinal transit were assessed before and after operation, during and after analgesic infusions. RESULTS: Pain intensity scores decreased similarly with morphine and tramadol infusions (total doses, 66.8+/-20 mg and 732.4+/-152 mg [mean +/- SD], respectively). Skin pain tolerance thresholds in the incisional dermatome remained similar with morphine and tramadol throughout the study. During morphine infusions, pain tolerance thresholds on the shoulder increased (P<0.05) and then decreased after discontinuation on day 4 (P<0.02) compared with before operation. Rectal distension pain tolerance pressure thresholds increased after operation during morphine infusions (P<0.05). Similar but nonsignificant trends occurred with tramadol. Orocecal and colonic transit times increased after operation with both morphine and tramadol (P<0.005), but gastric emptying was prolonged only with morphine (P = 0.03). AU motility and sensory parameters had returned to preoperative levels by 1 month after operation. CONCLUSIONS: Pain control was equally effective with morphine and tramadol infusions. No somatic or visceral sensitization was evident during morphine and tramadol infusions, but pain tolerance thresholds as markers of antinociception were increased more during morphine infusions. The significant sensitization seen only after morphine discontinuation may be due to convergent visceral input. Gut motility was prolonged significantly by visceral surgery itself and also by morphine.

Adult↗
PubMed1999

Genetics in obstetricians' offices: a survey study.

OBJECTIVE: To investigate obstetricians' genetic knowledge base and practice trends. METHODS: A questionnaire survey was sent to 1003 ACOG Fellows, 554 (55%) of whom responded. Results from the 446 respondents practicing obstetrics are reported. RESULTS: The majority of obstetricians surveyed (85.6%) reported completing standardized genetic-history forms for prenatal patients, and about half (48%) performed their own invasive diagnostic procedures. Most (87%) had access to genetic counselors. For aneuploidy risks associated with advanced maternal age, up to 69% of respondents provided at least some patient counseling in their offices. Physician knowledge of risk assessment and diagnostic testing in the areas of aneuploidy and neural tube defects was very good; however, for single-gene disorders such as cystic fibrosis, Tay-Sachs disease, and sickle cell disease, correct risk assessment or appropriate test selection presented difficulties for at least half of the respondents. Respondents cited the rapidity of changes in genetic testing as the greatest obstacle to providing genetic information to patients. CONCLUSION: Obstetricians' knowledge of inheritance and test selection pertaining to single-gene disorders was more limited than that for aneuploidy and neural tube defects. Comparable deficits were noted in patient-education efforts for single-gene disorders.

Congenital Abnormalities↗
PubMed1998

Dopamine markers and general cognitive ability.

Because general cognitive ability (g) is among the most heritable behavioural traits, it is a reasonable target for a search for quantitative trait loci (QTLs). We used a selected-extremes design to test candidate genes for allelic association with g. Polymorphisms in four genes in the dopamine system (DRD2, DRD3, DRD4, DAT1) were genotyped for 51 high g children with IQ scores > 130 and for 51 average g control children. No significant allelic or genotypic differences were found between the high g and average g groups for these markers of the dopamine system, even though the selected-extremes design provides power to detect QTL associations that involve a relative risk of about 1.5.

Adolescent↗
PubMed1998

The long-term outcome of cognitive behaviour therapy for adults in routine clinical practice.

It is recognised that there is a comparative lack of evidence on the long-term outcome of cognitive behavioural therapy for patients seen in ordinary clinical settings, as opposed to research trials. This paper presents some data on the outcome of 36 adult patients followed up an average of nearly two years after the end of therapy in a National Health Service CBT clinic. Whilst the vagaries of data collection in clinical practice mean that the generalisability of these results is still tentative, they suggest that the outcome at the end of treatment was generally well-maintained over the follow-up period, with most patients maintaining fairly stable scores on the measures used, and the rest roughly equally divided between those who deteriorated and those who improved further. A high proportion of patients at follow-up reported that they were still using various CBT strategies which they had learnt during therapy.

Adult↗
PubMed1998

Management of diabetes by obstetrician-gynecologists.

OBJECTIVE: To examine the rates of diagnosis and treatment of diabetes mellitus by ACOG Fellows in pregnant and nonpregnant patients. METHODS: We sent a questionnaire to 1250 ACOG Fellows. Thirty-nine percent responded. Responses were examined for potential differences between recently and less recently trained obstetrician-gynecologists. RESULTS: Ninety-six percent of obstetricians routinely screen for gestational diabetes mellitus (GDM). Fifty-five percent of obstetrician-gynecologists screen for diabetes in nonpregnant patients if there is a history of diabetes in the patient's family. Moreover, 33% care for women with type-1 diabetes mellitus, and 39% for women with type-2 diabetes mellitus who are not pregnant. Sixty-two percent believed that their patients with GDM are at increased risk for developing nongestational diabetes later in life, and 71% will recommend an evaluation of glucose tolerance in the future for these women. Finally, 99% are willing to prescribe oral contraceptives to women diagnosed previously with GDM. CONCLUSION: Obstetrician-gynecologists are aware of the need to screen for GDM and the importance of postpartum follow-up in GDM patients to detect type-2 diabetes mellitus. This practice is important because half of the 14 million people with type-2 diabetes mellitus are unaware they have this disorder, and many learn about it only after a serious complication has occurred.

Diabetes Mellitus↗