Search PubMed⌕ Search

Biomedical subjects

H Richards

Publications and source records attributed to H Richards.

At least 37 records · Page 2Linked to original sources
PubMed1996

Retrograde percutaneous gastrostomy and gastrojejunostomy in 505 children: a 4 1/2-year experience.

PURPOSE: To evaluate a technique of retrograde insertion of gastrostomy and gastrojejunostomy tubes with radiologic guidance in children. MATERIALS AND METHODS: During a 4 1/2-year period, 511 patients underwent attempted insertion of gastrostomy or gastrojejunostomy tubes. Patients' ages ranged from premature to 18.6 years (mean age, 3.8 years), and weight range was 0.8-86.0 kg (mean weight, 12 kg). The charts of 453 patients were reviewed. RESULTS: Placement was unsuccessful in six patients because of colonic interposition (n = 2), microgastria (n = 2), or hepatosplenomegaly (n = 2). Initial placement was a gastrostomy tube in 436 patients and a gastrojejunostomy tube in 69 patients. Sixty-eight gastrostomy tubes were converted to gastrojejunostomy tubes. Early complications (< 30 days) included skin infection (n = 11), stoma irritation (n = 20), and tube dislodgment (n = 6). Late complications included stoma irritation (n = 29), skin infection (n = 23), tube leakage (n = 14), and discomfort during feeding (n = 15). Two complications necessitated surgery: extragastric misplacement and small-bowel transgression. There were no tube-related deaths. CONCLUSION: Percutaneous retrograde placement of gastrostomy or gastrojejunostomy tubes safely and effectively provides long-term nutrition for children. A team approach is essential to provide service to this cumulative population.

Adolescent↗
PubMed1995

Child and adolescent psychiatric presentations of second-generation Afro-Caribbeans in Britain.

BACKGROUND: A clinical sample was used to investigate whether second-generation Afro-Caribbean children differed from other British-born children in their psychiatric presentation or vulnerability to risk factors. METHOD: Second-generation Afro-Caribbean patients (n = 292) were compared with a predominantly white group of patients (n = 1311) who lived in the same inner-city area and attended the same child psychiatric clinic between 1973 and 1989. Data on psychiatric presentation and background factors were systematically recorded at the time of the initial clinical assessment. RESULTS: Afro-Caribbean patients were exposed to more socio-economic disadvantage but less family dysfunction. The ratio of emotional to conduct disorders was lower among Afro-Caribbean than among the comparison patients--an effect that was not evidently due to demographic factors or diagnostic bias. Most risk factors for emotional or conduct disorders had comparable effects on Afro-Caribbean and comparison patients. Psychotic and autistic disorders were disproportionately common among the Afro-Caribbean patients. CONCLUSIONS: Second-generation Afro-Caribbean children differ somewhat from other British-born children in their psychiatric presentation--a difference that has persisted over the 1970s and 1980s and that deserves more investigation than it has received to date.

Acculturation↗
PubMed1994

Frequency-dependent properties of cerebral blood transport--an experimental study in anaesthetized rabbits.

Carotid arterial blood pressure and blood flow velocity in the basilar artery were studied in nine New Zealand rabbits under general anaesthesia. The cerebrovascular impedances for mean and maximal flow velocity were defined as the ratios of the respiratory and pulse waveforms of arterial blood pressure and blood flow velocities. The absolute values of these impedances were expressed and analysed as functions of frequency. Both functions decreased as frequency increased, demonstrating that a pulsatile blood movement need a lower energy expenditure than a continuous one. A minimum absolute value of impedance for flow velocity mean was found near 2.5-4 Hz in each rabbit. The impedance for mean flow velocity could be modelled by a second-order circuit, whereas the distribution of impedance for the maximal velocity had a more uniform character and could be approximated by a first-order model. A method of assessment of changes in cerebrovascular resistance using frequency properties of calculated impedance was proposed.

Animals↗
PubMed1994

Assessment of cerebral autoregulation with ultrasound and laser Doppler wave forms--an experimental study in anesthetized rabbits.

The aim of the study was to correlate changes in transcranial Doppler blood flow velocity wave form in the basilar artery with cortical red blood cell flux measured with a laser Doppler flowmeter during hemorrhage-induced hypotension in anesthetized and ventilated New Zealand rabbits. Although systolic flow velocity and flux exhibited an autoregulatory threshold at 45 mm Hg, diastolic flow velocity started to fall when mean arterial blood pressure fell below 65 mm Hg. The difference between the mean arterial blood pressure at which diastolic blood flow velocity decreases and the pressure at which mean flux decreases is the difference between systolic and diastolic blood pressure. The increasing divergence between systolic and diastolic flow velocities was reflected in an increase in the amplitude of blood flow velocity pulsations and pulsatility indices. An increase in flux pulsatile wave form was noted as cerebral resistive vessels dilated with hypotension.

Animals↗
PubMed1993

Identification of the minimal replicon of the streptomycete plasmid pIJ101.

The minimal replicon of pIJ101 was defined to a 2.0-kb BalI-SacII fragment containing the rep ORF and a non-coding region of DNA, but not orf56 (pQR435). This non-coding region of DNA was found to be crucial for plasmid replication in Streptomyces lividans and may contain either the origin of replication or the rep promoter (or both). A 1.4-kb NotI-SacII fragment containing only the rep ORF produced a 54-kDa protein in vitro when expressed from the lacZ promoter. pQR435 was structurally unstable in S. lividans and accumulated single-stranded (ss)DNA. The insertion of the site for second-strand initiation (ssi) into pQR435 did not prevent the plasmid from rearranging or from accumulating ssDNA.

DNA Replication↗
PubMed1993

Analysis of the site for second-strand initiation during replication of the Streptomyces plasmid pIJ101.

The indigenous plasmid pIJ101 is the parent of many cloning vectors used in Streptomyces. One early pIJ101 derivative, pIJ702, has been particularly widely used. pIJ702 lacks sti:cop/korB and accumulates single-stranded DNA (ssDNA). The 1.2 kb BclI-BclI sti:cop/korB and 0.7 kb SpeI-BclI sti regions were isolated from pIJ101 and cloned into pIJ702 at the PstI site in both orientations. No ssDNA was detected in constructs containing sti present in its correct orientation with respect to the basic replicon, with or without cop/korB. Constructs which contained sti in the reverse orientation did accumulate ssDNA. Thus, sti is only active as the site for second-strand synthesis in its natural orientation. Furthermore, sti inserted in either orientation into the structurally unstable pIJ702-pUC8 shuttle vectors prevented them from rearranging in S. lividans. The sti function was defined to a 0.53 kb SpeI-SacII fragment and the probable site for second-strand initiation (ssi) was identified.

Base Sequence↗
PubMed1993

Seasonal changes in rule infractions among prisoners: a preliminary test of the temperature-aggression hypothesis.

To test the temperature-aggression hypothesis, seasonal changes in aggression as indexed by reported rule infractions were studied for prisoners located at the Patuxent Institution, Jessup, Maryland. 5383 reports of rule infractions occurred between July 1987 and March 1991. Rule infractions occurred more frequently during the hot summer months than the three other seasons of the year. This summer effect, though significant, is only a few percent above a theoretical chance level based on the number of days comprising the seasons. A much stronger monthly effect over 45 months was found, but the bases of erratic fluctuations are not known.

Aggression↗
PubMed1992

Expression and characterisation of the korB gene product from the Streptomyces lividans plasmid pIJ101 in Escherichia coli and determination of its binding site on the korB and kilB promoters.

A 0.5kb Spel-BclI fragment containing the pIJ101 korB ORF was cloned into pUC8 under the control of the lacZ promoter, creating pQR206. In vitro coupled transcription-translation of pQR206 identified a protein product of approximately 10kDa, which corresponds to the predicted molecular weight deduced from the korB sequence. pQR206 was used to express the 10kDa KorB protein in vivo in E. coli. Crude E. coli protein extracts containing KorB were shown to bind to a 0.8kb kilB fragment and a 0.5kb korB fragment in gel retardation assays. DNasel footprinting indicated that the DNA recognition sequence of the KorB protein lies within a 60bp protected region encompassing the kilB promoter and a 36bp region encompassing the korB promoter.

Bacterial Proteins↗
PubMed1992

Day-case paediatric surgery: the only choice.

Since January 1989 a policy of day-case surgery has been adopted for suitable paediatric procedures by one firm (MEF) at East Glamorgan Hospital. There have been 184 children treated to date, with an age range of 4 weeks to 13 years. There were 58 circumcisions, 48 hernias, 35 orchidopexies, 18 hydrocoeles and 25 miscellaneous procedures performed with no significant complications. All children were given a general anaesthetic, 42 procedures (22%) were performed using endotracheal intubation, the remainder with a facemask. Postoperative analgesia was provided in most cases by local wound infiltration with bupivacaine 0.25%. The average length of stay before January 1989 was 3 days and 2 nights for similar cases. Cost analysis shows significant potential financial savings of 105 pounds per patient treated. The implications for future planning are discussed.

Adolescent↗
PubMed1988

Chemical synthesis, cloning and expression in mammalian cells of a gene coding for human tissue-type plasminogen activator.

A 1610-bp DNA duplex coding for human tissue-type plasminogen activator has been chemically synthesized using the phosphoramidite procedure, adapted for a custom-built gene synthesizer. The synthesizer, which was designed for both simplicity and speed, permits the rapid construction of relatively large genes and compares favorably in speed with alternative cDNA isolation procedures. The plasminogen activator gene has been expressed in mammalian cells and shown to produce authentic protein by an immuno-activity assay.

Base Sequence↗