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Biomedical subjects

J Hill

Publications and source records attributed to J Hill.

At least 181 records · Page 10Linked to original sources
PubMed1996

The effect of electrode position in electrocochleography.

This study assessed the effect of needle electrode position on the human cochlear summating potential (SP) obtained by transtympanic electrocochleography (ECochG). Electrocochleography was performed on 10 subjects with large central tympanic membrane perforations with good cochlear function, and in whom a needle electrode could be accurately placed in a series of five pre-determined positions in the middle ear. A comparison of the electrocochleograms revealed a wide scatter of results between different positions in the same patient and between similar positions in different patients. Only when the needle was repositioned at an almost identical recording site in the same subject, was good reproducibility achieved. Such a wide and unpredictable variation in results would suggest great caution is needed when comparing traces obtained using a transtympanic technique which precludes a view of the electrode tip.

Adult↗
PubMed1996

Assessment of personality functioning in the transition from adolescent to adult life: preliminary findings.

BACKGROUND: The Adolescent to Adult Personality Functioning Assessment (ADAPFA) a modification of the Adult Personality Functioning Assessment (APFA) is described. It may be used to assess specific and general social dysfunction in the transition from childhood to adult life. METHOD: Two raters independently rated 38 audiotaped interviews to test the interrater reliability of the instrument. The relationship between dysfunction in specific domains and overall psychosocial dysfunction was examined. RESULTS: Interrater reliabilities for the total ADAPFA score and for the majority of the domains were high. Agreement on type of dysfunction and on categorical ratings indicating the presence of personality disorder were good. CONCLUSION: The ADAPFA is a useful measure of interpersonal and social role performance in the transition between adolescent and adult life.

Adolescent↗
PubMed1996

Biomass accumulation in hydroponically grown sweetpotato in a controlled environment: a preliminary study.

In the development of a plant growth model, the assumptions made and the general equations representing an understanding of plant growth are gradually refined as more information is acquired through experimentation. One such experiment that contributed to sweetpotato model development consisted of measuring biomass accumulation of sweetpotato grown in hydroponic culture in a plant growth chamber. Plants were started from fifteen centimeter long 'TU-82-155' sweetpotato vine cuttings spaced 25 cm apart in each of 18 rectangular growing channels (0.15 by 0.15 by 1.2m) in a system designed to use the nutrient film technique (NFT). Each channel contained four plants. The 3.5m by 5.2m plant growth chamber environmental parameters included an 18h photoperiod, 500 micromoles m-2 s-1 of photosynthetic photon flux (PPF), and a diurnal light/dark temperature of 28 degrees C/22 degrees C. The relative humidity was 80 +/- 5% and the CO2 partial pressure was ambient (350 ppm). The nutrient solution contained in 30L reservoirs was a modified half Hoagland's solution with a 1:2.4 N:K ratio and a pH of 6.2. Solution replenishment occurred when the electrical conductivity (EC) level dropped below 1050. Plants were harvested at 15 days after planting (DAP) and weekly thereafter until day 134. By 57 DAP, stems and fibrous roots had acquired 90% of their total dry biomass, while leaves had reached 84% of their maximum dry biomass. Beginning at 64 DAP dry biomass accumulation in the storage roots dominated the increase in dry biomass for the plants. Dry weight of storage roots at 120 DAP was 165 g/plant or 1.1 kg/m2. Resulting growth curves were consistent with the physiological processes occurring in the plant. Results from this study will be incorporated in a plant growth model for use in conjunction with controlled life support systems for long-term manned space missions.

Biomass↗
PubMed1996

Elevated carbon dioxide influences yield and photosynthetic responses of hydroponically-grown [correction of glown] sweetpotato.

The response of 'TI-155' and 'Georgia Jet' sweetpotato cultivars to elevated CO2 concentrations of 400 (ambient), 750 and 1000 micromoles mol-1 were evaluated under controlled environment conditions using the nutrient film technique (NFT). Growth chamber conditions included photosynthetic photon flux (PPF) of 600 micromoles m-2 s-1, 14/10 light/dark period, and 70% +/- 5% RH. Plants were grown using a modified half-Hoagland nutrient solution with a pH range of 5.5-6.0 and an electrical conductivity of 0.12 S m-1. Gas exchange measurements were made using infrared gas analysis, an open-flow gas exchange system, and a controlled-climate cuvette. Photosynthetic (Pn) measurements were made at CO2 ranges of 50 to 1000 micromoles mol-1. Storage root yield/plant increased with CO2 up to 750 but declined at 1000 micromoles mol-1. Storage root dry matter (DM) and foliage dry weight increased with increasing CO2. Harvest index (HI) for both cultivars was highest at 750 micromoles mol-1. The PPF vs Pn curves were typical for C3 plants with saturation occurring at approximately 600 micromoles m-2 s-1. CO2 concentration did not significantly influence net Pn, transpiration, water-use-efficiency (WUE), and stomatal conductance. As measurement CO2 concentration increased, net Pn and WUE increased while transpiration and stomatal conductance decreased.

Biomass↗
PubMed1996

Palliative performance scale (PPS): a new tool.

The Palliative Performance Scale (PPS), a modification of the Karnofsky Performance Scale, is presented as a new tool for measurement of physical status in palliative care. Its initial uses in Victoria include communication, analysis of home nursing care workload, profiling admissions and discharges to the hospice unit, and, possibly, prognostication. We assessed 119 patients at home, of whom 87 (73%) had a PPS rating between 40% and 70%. Of 213 patients admitted to the hospice unit, 175 (83%) were PPS 20%-50% on admission. The average period until death for 129 patients who died on the unit was 1.88 days at 10% PPS upon admission, 2.62 days at 20%, 6.70 days at 30%, 10.30 days at 40%, 13.87 days at 50%. Only two patients at 60% or higher died in the unit. The PPS may become a basis for comparing drug costs at home and for studying the effects of treatments (e.g. hypodermoclysis) at various levels of physical performance. Validity and reliability testing are currently being undertaken.

British Columbia↗
PubMed1996

The value of routine computed tomography of the brain in the pre-operative assessment of patients for carotid endarterectomy.

OBJECTIVE: To determine the prevalence of brain infarcts and other intracranial pathology on computed tomography (CT) in patients with greater than 50% internal carotid artery stenosis. DESIGN: Descriptive study of CT findings. SETTING: Referral-based cohort at Groote Schuur Hospital. PARTICIPANTS: Sixty-three patients aged 40-82 years who had CT of the head prior to carotid endarterectomy. MAIN OUTCOME MEASURES: Prevalence of brain infarct in patients presenting with transient ischaemic attack (TIA) or stroke, and yield of unsuspected intracranial pathology other than ischaemic necrosis. RESULTS: Brain infarcts were diagnosed in 54% of patients presenting with TIA and in 73% of patients with stroke. True-positive CT scans were present in only 19% and 44% of patients with TIA and stroke, respectively. A single incidental frontal lobe granuloma, unrelated to the patient's clinical presentation, was noted. CONCLUSIONS: In the selected group of patients referred for carotid endarterectomy, routine use of CT of the head is not indicated and can be reserved for cases with extraordinary clinical features.

Adult↗
PubMed1995

Accuracy of laboratory and portable monitor international normalized ratio determinations. Comparison with a criterion standard.

BACKGROUND: Portable instruments that measure the prothrombin time and automatically calculate the international normalized ratio (INR) with the use of a drop of whole blood have simplified the treatment of patients who are receiving warfarin therapy. The accuracy of these portable monitors has never been determined by comparing INR results with a criterion (gold) standard INR determination. METHODS: Duplicate whole-blood INR determinations were made with two commercially available portable INR monitors. Duplicate frozen-plasma samples were measured with four different thromboplastin reagents, each with a different international sensitivity index. The criterion standard INR was determined by using an international reference thromboplastin and the manual tilt-tube technique. Agreement was evaluated by determining how accurately laboratory and monitor INR determinations matched criterion standard values in designating a sample to be within or outside of currently recommended INR target ranges. RESULTS: Two of the laboratory methods, which used relatively sensitive thromboplastins, showed close agreement with the criterion standard, whereas two laboratory methods that used less sensitive thromboplastin reagents showed poor agreement. Both of the portable monitors fell between these extremes. The two best laboratory methods ere significantly better (P < .003) than both monitors, which in turn were better (P < .003) than the remaining two laboratories. CONCLUSIONS: There is large interlaboratory variation in the accuracy of INR determinations. Laboratory methods that used insensitive (high international sensitivity index) thromboplastins performed poorly. Accuracy of monitor measurements appears satisfactory.

Adult↗
PubMed1995

Exploring the binding preferences/specificity in the active site of human cathepsin E.

Aspartic proteinases are produced in the human body by a variety of cells. Some of these proteins, examples of which are pepsin, gastricsin, and renin, are secreted and exert their effects in the extracellular spaces. Cathepsin D and cathepsin E on the other hand are intracellular enzymes. The least characterized of the human aspartic proteinases is cathepsin E. Presented here are results of studies designed to characterize the binding specificities in the active site of human cathepsin E with comparison to other mechanistically similar enzymes. A peptide series based on Lys-Pro-Ala-Lys-Phe*Nph-Arg-Leu was generated to elucidate the specificity in the individual binding pockets with systematic substitutions in the P5-P2, and P2'-P3' based on charge, hydrophobicity, and hydrogen bonding. Also, to explore the S2 binding preferences, a second series of peptides based on Lys-Pro-Ile-Glu-Phe*Nph-Arg-Leu was generated with systematic replacements in the P2 position. Kinetic parameters were determined for both sets of peptides. The results were correlated to a rule-based structural model of human cathepsin E, constructed on the known three-dimensional structures of several highly homologous aspartic proteinases; porcine pepsin, bovine chymosin, yeast proteinase A, human cathepsin D, and mouse and human renin. Important specificity-determining interactions were found in the S3 (Glu-13) and S2 (Thr-222, Gln-287, Leu-289, Ile-300) subsites.

Amino Acid Sequence↗
PubMed1995

Head injuries in lateral impact collisions.

Individual non-minor injuries (Abbreviated Injury Scale (AIS) > or = 2) to the head that occurred to belted and unbelted drivers and front seat passengers on the stuck side of impacted vehicles were examined. Injury type, injury combination, collision severity in relation to type of injury as well as contact sources were assessed. Forty-eight percent of injuries were moderate in severity (AIS 2). The most common type of injury was the diffuse brain injury, typically marked by a short period of unconsciousness, which occurred in collisions of lower severity than focal brain and skull fracture injuries. One-hundred and five out of 216 (48.6%) of contact sources for all injury types originated from outside the vehicle and such exterior sources were more likely to result in high severity injuries. Thirty percent of injuries resulted from head contacts with other vehicles. The most frequent vehicle interior contact source was the side window glass. Diffuse injuries tended to occur independently of other injury types and were more likely to originate from an interior rather than exterior contact. Preventative measures for head injury reduction in lateral collisions are discussed. Overall, the data show that proposed and present European and U.S. lateral impact test methods do not address many head injury problems such as those included in this study.

Abbreviated Injury Scale↗
PubMed1995

Massive chronic intervillositis associated with recurrent abortions.

Massive chronic intervillositis (MCI) is an unusual placental lesion associated with poor fetal growth and adverse pregnancy outcome; it has not previously been associated with spontaneous abortion or recurrent pregnancy loss. This article reports a patient who had 10 spontaneous abortions with repetitious massive chronic intervillositis documented in four of five gestations spanning all three trimesters. Characteristic placental histology induced massive infiltration of the maternal intervillous space by chronic inflammatory cells and fibrin, without associated chronic villitis; the cellular infiltrate was composed predominantly of LCA and CD68 immunoreactive cells with scattered CD45RO positivity, consistent with a monocyte/macrophage population with occasional T lymphocytes. Elevated maternal serum alpha-fetoprotein was documented in two pregnancies. These findings support the concept that this unusual placental lesion may have an immunologic basis, and suggest that MCI may be a histopathologically recognizable cause of recurrent spontaneous abortion.

Abortion, Habitual↗
PubMed1995

A study of the variability of training and beliefs among professionals who interview children to investigate suspected sexual abuse.

The study aimed to examine the relationship between professional background, number of qualifications, specific training in child sexual abuse and beliefs about indicators of child sexual abuse in professionals who conduct sexual abuse investigatory interviews. A questionnaire was sent to all professionals within a discrete geographical area who were involved in the investigation of child sexual abuse. One hundred and six of 136 questionnaires were returned (77.9%), 60 of which were from investigatory interviewers. The latter comprised eight different professions. There was a considerable variation in general training and in training in child sexual abuse specifically, both of which were more likely to have been received by medical psychological and social work respondents than residential care workers and police officers. Beliefs about sexual abuse indicators showed a striking variation between respondents. Most of the variation was not accounted for by the respondent variables examined. Where there was evidence for an association, the interviewer's professional background had the strongest effect, followed by the number of qualifications and the number of investigatory interviews conducted per year. Previous training in child sexual abuse had no significant effect on these beliefs. Further research is needed into the optimal training necessary for members of different professions in order to change their beliefs about child sexual abuse.

Adult↗
PubMed1995

Exogenous retinoic acid causes specific alterations in the development of the midbrain and hindbrain of the zebrafish embryo including positional respecification of the Mauthner neuron.

Exogenously applied retinoic acid given at the early stages of gastrulation causes abnormal development of the caudal midbrain and anterior hindbrain in vertebrate embryos. We describe the limits of the brain regions that are affected using neuroanatomical criteria in the zebrafish embryo. Analysis of the reticulospinal complex shows that the Mauthner cell, which normally differentiates in rhombomere 4, is duplicated either in this rhombomere or in rhombomere 2. Using probes for zebrafish krx20 and pax2, it is demonstrated that retinoic acid affects the expression domains of these regulatory genes in a manner that is consistent with the neuroanatomical data. Expression of the goosecoid gene, which expressed in the prospective anterior mesoderm from the onset of gastrulation, is unaffected by the doses of retinoic acid used in this study, reflecting the normal development of the anterior end of the embryo.

Animals↗