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Biomedical subjects

M Griffith

Publications and source records attributed to M Griffith.

At least 55 records · Page 3Linked to original sources
PubMed1998

Prenatal risk factors for cryptorchidism: a record linkage study.

Using data from the Oxford Record Linkage Study (ORLS), we conducted a case-control study to examine prenatal risk factors for cryptorchidism. We identified 1449 boys born during 1970-86 for whom there was a record of an orchidopexy during 1970-87. Up to eight controls were matched to each case on year of birth and hospital or place of delivery. For each boy and his mother we extracted abstracts of maternity and general hospital records from the ORLS. Low birthweight (trend P < 0.001), low social class (trend P < 0.001), breech presentation (relative risk 1.67; 95% confidence interval [CI] 1.16, 2.41), pre-eclampsia (1.17 [1.00, 1.37]), artificial feeding (1.22 [1.04, 1.45]) and episiotomy (1.13 [1.00, 1.27]) were identified as independent risk factors for cryptorchidism. Gestational age was not independently associated with cryptorchidism after adjusting for birthweight (P = 0.33), and this observation suggested that some cryptorchid boys may have suffered from intrauterine growth retardation. Low birthweight, breech presentation and pre-eclampsia may have in common poor placental function and impaired fetal growth, which may be causes of cryptorchidism.

Bottle Feeding↗
PubMed1998

A review of mind-body therapies in the treatment of cardiovascular disease. Part 1: Implications for the elderly.

BACKGROUND: A review of research on complementary and alternative treatments, specifically mind-body techniques, was conducted at Stanford University. The goals of the review were to establish a comprehensive literature review and to provide a rationale for future research concerning successful aging. METHODS: Computerized searches were conducted using MEDLINE, PsychInfo, Stanford Library, Dissertation Abstracts, Lexus-Nexus, the Internet, and interviews conducted with practitioners. All studies since 1990 that examined mind-body treatments of cardiovascular disorders in the elderly were included. Mind-body practices evaluated were social support, cognitive-behavioral treatment, meditation, the placebo effect, hope, faith, imagery, spiritual healing, music therapy, hypnosis, yoga, t'ai chi, qigong and aikido. Studies conducted after 1990 were a priority, but when more recent literature was scarce, other studies using randomized, controlled trials were included. RESULTS: Mind-body techniques were found to be efficacious primarily as complementary and sometimes as stand-alone alternative treatments for cardiovascular disease-related conditions. Studies provided evidence for treatment efficacy, but the need for further controlled research was evident. CONCLUSIONS: Reviewers found only a handful of randomized, controlled research studies conducted in the United States. As a result, there is a lack of replicated studies with which to determine appropriate treatment dosage and the mechanisms by which many of the practices work. Compelling anecdotal evidence, the presence of some controlled research, overall cost effectiveness, and the lack of side effects resulting from mind-body treatments make further investigation a high priority.

Aged↗
PubMed1998

Properties of whole-cell ionic currents in cultured human corneal epithelial cells.

PURPOSE: To identify and partially characterize the ionic currents contributing to the whole-cell conductance of cultured human corneal epithelial cells. METHODS: Epithelial cells were scraped from human donor corneas and cultured for use in patch-clamp experiments. Amphotericin B and the perforated-patch configuration were used to measure whole-cell currents in cells isolated from confluent monolayers. RESULTS: Cell monolayers exhibited cobblestone morphology and were immunopositive for corneal epithelium-specific cytokeratin. Single cells had a capacitance of 21 +/- 2 pF and expressed similar types of ionic currents regardless of passage number. In descending order of frequency of occurrence, cells exhibited a nonselective cation current active at depolarized voltages and insensitive to Ba2+ and Gd3+; an outwardly rectifying K+ current active at depolarized voltages, stimulated by flufenamic acid and inhibited by tetraethylammonium; a voltage-gated inward Na+ current; an outwardly rectifying K+ current active at hyperpolarized voltages, stimulated by flufenamic acid, blocked by Ba2+, and insensitive to diltiazem; an inwardly rectifying K+ current; and a nonselective cation current inhibited by flufenamic acid. CONCLUSIONS: Our results are consistent with those in previous studies of noncultured epithelia from rabbit and human corneas showing an outwardly rectifying K+ current active at hyperpolarized voltages and a nonselective cation current active at depolarized voltages and insensitive to Ba2+. These data suggest cultured cells may be useful in determining the physiological role of ion channels in corneal epithelia and may aid in the development of a cell-based model for the examination of the effects of wounding and toxic agents on the human cornea.

Amphotericin B↗
PubMed1997

Midkine and secondary neurulation.

Midkine (MK) is a growth factor with documented neurotrophic activity for central nervous system neurons. It has also been shown to induce conversion of pluripotent mesenchymal P19 embryonic carcinoma cells into neuroepithelial derivatives. During the development of the chick embryonic neuraxis, two separate events occur. The anterior, greater portion of the neural tube, the primary neural tube, develops first from the neuroectoderm. The posterior section of the neural tube or the secondary neural tube forms next, from the cells of the tail bud, as tail bud cells undergo mesenchymal-neuroepithelial conversion. Disruptions in tail bud differentiation lead to defects of the secondary neural tube. In this study, antisense oligodeoxynucleotides (ODNs) were used to inhibit MK expression in order to determine if MK has a role in the mesenchymal-neuroepithelial conversion process. Chick embryos at the tail bud anlagen stage were treated with antisense ODNs to MK mRNA by sub-blastodermal injection and reincubated for 24 or 48 hr. The antisense ODN treatment resulted in a significant increase in the incidence of secondary neural tube defects, compared to control treatments with the saline vehicle only, sense ODNs, scrambled antisense ODNs, or non-sense ODNs. The loss of MK mRNA in the antisense ODN-treated embryos was confirmed by in situ hybridization. The results therefore suggest a role for MK in the mesenchymal-neuroepithelial conversion of tail bud mesenchyme into the secondary neural tube.

Animals↗
PubMed1996

An immune response to ice crystals in North Atlantic fishes.

In mammals, the presence of crystals composed of small organic molecules, including urate and related compounds, has been shown to trigger an inflammatory response and the subsequent production of specific immunoglobulins (Ig's). Many fishes that are exposed to ice crystals in cold temperate and polar oceans may harbour ice crystals internally. Here, we report evidence for a specific immune response to ice crystals in cold-ocean marine fishes. Using ice nucleation activity as an assay, anti-ice Ig's were detected in the sera of the cold-ocean marine fish species, ocean pout (Macrozoarces americanus) and Atlantic herring (Clupea harengus harengus), but not in the sera of species that are not exposed to ice. Purified Ig's isolated from ocean pout serum using two different protocols showed ice nucleation activity, thus demonstrating the presence of ice binding specificity among these Ig's.

Animals↗
PubMed1995

Antifreeze proteins and their potential use in frozen foods.

Antifreeze proteins (AFPs) are proteins that have the ability to modify the growth of ice, resulting in the stabilization of ice crystals over a defined temperature range and in the inhibition of the recrystallization of ice. AFPs are found in a wide range of organisms, including bacteria, fungi, plants, invertebrates and fish. Moreover, multiple forms of AFPs are synthesized within each organism. As a result, it should be possible to select an AFP with appropriate characteristics and a suitable level of activity for a particular food product. Antifreeze proteins may improve the quality of foods that are eaten while frozen by inhibiting recrystallization and maintaining a smooth texture. In foods that are frozen only for preservation, AFPs may inhibit recrystallization during freezing, storage, transport and thawing, thus preserving food texture by reducing cellular damage and also minimizing the loss of nutrients by reducing drip. Antifreeze proteins are naturally present in many foods consumed as part of the human diet. However, AFPs may be introduced into other food products either by physical processes, such as mixing and soaking, or by gene transfer.

Journal Article↗
PubMed1995

Antifreeze proteins in winter rye are similar to pathogenesis-related proteins.

The ability to control extracellular ice formation during freezing is critical to the survival of freezing-tolerant plants. Antifreeze proteins, which are proteins that have the ability to retard ice crystal growth, were recently identified as the most abundant apoplastic proteins in cold-acclimated winter rye (Secale cereale L.) leaves. In the experiments reported here, amino-terminal sequence comparisons, immuno-cross-reactions, and enzyme activity assays all indicated that these antifreeze proteins are similar to members of three classes of pathogenesis-related proteins, namely, endochitinases, endo-beta-1,3-glucanases, and thaumatin-like proteins. Apoplastic endochitinases and endo-beta-1,3-glucanases that were induced by pathogens in freezing-sensitive tobacco did not exhibit antifreeze activity. Our findings suggest that subtle structural differences may have evolved in the pathogenesis-related proteins that accumulate at cold temperatures in winter rye to confer upon these proteins the ability to bind to ice.

Adaptation, Biological↗
PubMed1995

Detection of loss of cerebral vascular tone by correlation of arterial and intracranial pressure signals.

With the use of a laboratory model, arterial and intracranial pressure signals were obtained under conditions of intact regulation of cerebral blood flow and massive dilation. During elevated intracranial pressure and intact regulation, positive pressure inhalation appears to briefly occlude venous flow into the cranial sinuses during inspiration. As a result, the intracranial pressure and arterial pressure signals are not similar. In contrast, when maximal dilation causes failure of regulation of cerebral blood flow, the intracranial pressure signal is approximately proportional to the arterial pressure signal. Comparison of the cross-correlation function derived from the intracranial and arterial pressure signals to the autocorrelation function of the arterial signal reveals that the two correlation functions are: 1) different during intact regulation and 2) nearly identical during dilation induced failure of regulation of cerebral blood flow.

Animals↗
PubMed1995

Low temperature growth, freezing survival, and production of antifreeze protein by the plant growth promoting rhizobacterium Pseudomonas putida GR12-2.

The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 was originally isolated from the rhizosphere of plants growing in the Canadian High Arctic. Here we report that this bacterium was able to grow and promote root elongation of both spring and winter canola at 5 degrees C, a temperature at which only a relatively small number of bacteria are able to proliferate and function. In addition, the bacterium survived exposure to freezing temperatures, i.e., -20 and -50 degrees C. In an effort to determine the mechanistic basis for this behaviour, it was discovered that following growth at 5 degrees C, P. putida GR12-2 synthesized and secreted to the growth medium a protein with antifreeze activity. Analysis of the spent growth medium, following concentration by ultrafiltration, by SDS-polyacrylamide gel electrophoresis revealed the presence of one major protein with a molecular mass of approximately 32-34 kDa and a number of minor proteins. However, at this point it is not known which of these proteins contains the antifreeze activity.

Antifreeze Proteins↗
PubMed1993

Computerised linking of medical records: methodological guidelines.

OBJECTIVES: To report on the development of computer assisted methods for linking medical records and record abstracts. DESIGN: The methods include file blocking, to put records in an order which makes searching efficient; matching, which is the process of comparing records to determine whether they do or do not relate to the same person; linkage, which is the process of assembling correctly matched records into a time sequenced composite record for the individual; and validation checks and corrections, in which any inconsistencies between different records for the same person are identified and corrected. SETTING: The dataset comprising the Oxford record linkage study which includes hospital inpatient records and vital records. RESULTS AND CONCLUSIONS: Probability matching, using an array of identifiers, achieves much higher levels of correct matching than is generally achievable by exact character by character comparisons. The increasing use of information technology to store data about health and health care means that there is increasing scope to link records for research and for patient care. Sophisticated methods to achieve this on a large scale are now available.

England↗
PubMed1992

Matrix NADH dehydrogenases of plant mitochondria and sites of quinone reduction by complex I.

In order to distinguish the pathways involved in the oxidation of matrix NADH in plant mitochondria, the oxidation of NADH and nicotinamide hypoxanthine dinucleotide (reduced form) was investigated in submitochondrial particles prepared from beetroot (Beta vulgaris L. cv. Derwent Globe) and soybeans (Glycine max L. cv. Bragg). Nicotinamide-hypoxanthine-dinucleotide(reduced form)-oxidase activity was more strongly inhibited by rotenone than the NADH-oxidase activity but both of the rotenone-inhibited activities could be stimulated by adding ubiquinone-1. The corresponding ubiquinone-1-reductase activities were inhibited by rotenone (to 69%) and further inhibited by N,N'-dicyclohexylcarbodiimide (to 79%), whilst the K3Fe(CN)6-reductase activities were not sensitive to either rotenone or N,N'-dicyclohexylcarbodiimide. Immunological analysis of mitochondrial proteins using an antiserum raised against purified beetroot complex I indicated very few differences between soybean and fresh and aged beetroot mitochondria, despite their varying sensitivities to rotenone. We confirm that there are two dehydrogenases capable of oxidising internal NADH and that only one of these, namely complex I, is inhibited by rotenone. Further, we conclude that complex I has two potential sites of quinone reduction, both sensitive to N,N'-dicyclohexycarbodiimide inhibition but only one of which is sensitive to rotenone inhibition.

Benzoquinones↗
PubMed1992

Transesophageal contrast echocardiography and color flow mapping: methods of choice for the detection of shunts at the atrial level?

The detection of shunts at the atrial level is important, and a reliable means of diagnosis is required. Precordial contrast echocardiography is usually performed to detect such shunts. To investigate the advantages of transesophageal echocardiographic techniques, we studied 167 consecutive patients with both precordial and transesophageal echocardiography, using two-dimensional imaging with contrast techniques (with and without a Valsalva maneuver) and color flow mapping. A patent foramen ovale was diagnosed in 31 patients, an atrial septal defect in 11 (7 with bidirectional shunts), and a pulmonary arteriovenous fistula in 3 patients. All right-to-left shunts were detected with transesophageal contrast echocardiography. With these results used as the gold standard, the sensitivity of combined precordial techniques was 37% and that of transesophageal color flow mapping 46%. All left-to-right shunts were detected by transesophageal color flow mapping. With these results used as the gold standard, the sensitivities of both precordial color flow mapping and a transesophageal negative right atrial contrast study were 27%. We conclude that transesophageal contrast echocardiography is the echocardiographic method of choice for the detection of a right-to-left shunt at the atrial level, which cannot be excluded by negative results on precordial study or on transesophageal color flow map study. A left-to-right shunt at this level is best detected by transesophageal color flow mapping.

Arteriovenous Fistula↗
PubMed1992

Antifreeze protein produced endogenously in winter rye leaves.

After cold acclimation, winter rye (Secale cereale L.) is able to withstand the formation of extracellular ice at freezing temperatures. We now show, for the first time, that cold-acclimated winter rye plants contain endogenously produced antifreeze protein. The protein was extracted from the apoplast of winter rye leaves, where ice forms during freezing. After partial purification, the protein was identified as antifreeze protein because it modified the normal growth pattern of ice crystals and depressed the freezing temperature of water noncolligatively.

Journal Article↗
PubMed1992

Recording of deaths in hospital information systems: implications for audit and outcome studies.

STUDY OBJECTIVE: The aim was to report on the extent to which death certificates which specify that death occurred in hospital can be matched and linked with routine hospital inpatient information systems. DESIGN: The study involved linkage of hospital records which specified that death occurred in hospital to corresponding death certificates; and linkage of death certificates which specified that death occurred in hospital to corresponding hospital records. SETTING: Six health districts in southern England covered by medical record linkage. SUBJECTS: Records were examined of patients aged 65 years and over, which specified that death occurred in hospital between 1979 and 1985. MAIN RESULTS: 98.2% of hospital record abstracts which specified that death occurred in hospital were linked by our standard computer-based techniques to death certificates. Conversely, however, only 94.4% of death certificates which specified that death occurred in hospital could be linked to the abstracts of corresponding hospital inpatient records. A major factor contributing to the latter failures may be a difference of definition of what constitutes a death "following hospital admission" in patients who die shortly after arrival at hospital. CONCLUSIONS: Linkage of hospital records to death certificates is both feasible and desirable. Error rates are generally small; but hospital inpatient record abstracts corresponding to death certificates for deaths in hospital may not invariably exist when death occurs shortly after the arrival of the patient at hospital.

Death Certificates↗