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Biomedical subjects

J C Walker

Publications and source records attributed to J C Walker.

At least 19 recordsLinked to original sources
PubMed1992

Human ectopic fascioliasis in Australia: first case reports.

OBJECTIVE: To describe the manifestations of two cases of migratory ectopic fascioliasis diagnosed in Australia, including the first report of lymphatic infection. PRESENTATION: Both patients presented with acute, superficial swellings. In the first, a 46-year-old woman, the lump was found to be a cervical lymph node containing a mature Fasciola hepatica which had released eggs into surrounding tissues. The second patient was a 34-year-old male abattoir worker, in whom the subcutaneous lesion resembled an infected sebaceous cyst and contained an immature fluke. FINDINGS: Both lesions were resected and diagnosed histologically. Fasciola eggs were not found in the faeces of either patient. Blood eosinophilia was not detected in either case. A serological test for fascioliasis was carried out in the second case and the result was positive. In both cases, infection was probably acquired in Australia, although neither patient had eaten watercress. OUTCOME: Neither patient was specifically treated with anthelminthic agents, and neither suffered further complications. CONCLUSION: Migratory fascioliasis occurs in Australia. It can present as superficial or deep focal lesions, not necessarily in association with peripheral blood eosinophilia or Fasciola eggs in faeces. Serological tests may be helpful in diagnosing such cases.

Adult↗
PubMed1992

Identification of a maize nucleic acid-binding protein (NBP) belonging to a family of nuclear-encoded chloroplast proteins.

A cDNA encoding a nuclear-encoded chloroplast nucleic acid-binding protein (NBP) has been isolated from maize. Identified as an in vitro DNA-binding activity, NBP belongs to a family of nuclear-encoded chloroplast proteins which share a common domain structure and are thought to be involved in posttranscriptional regulation of chloroplast gene expression. NBP contains an N-terminal chloroplast transit peptide, a highly acidic domain and a pair of ribonucleoprotein consensus sequence domains. NBP is expressed in a light-dependent, organ-specific manner which is consistent with its involvement in chloroplast biogenesis. The relationship of NBP to the other members of this protein family and their possible regulatory functions are discussed.

Amino Acid Sequence↗
PubMed1992

Assessing the effects of odorants on nasal airway size and breathing.

A technique was developed to obtain continuous measurements of both respiratory behavior and nasal patency in response to well-controlled odorant stimulation. An automated apparatus similar to that described by Walker et al. (27) was used to present precise concentrations of an odorant. The pressure-flow technique (28) was used to continuously measure nasal airway cross-sectional area, nasal airflow rate, air volume and time characteristics associated with breathing before and during odorant stimulation. Immediately following each odorant presentation, subjects entered their psychophysical responses into a microcomputer via an electronic mouse. Respiratory and psychophysical responses of ten normal subjects to four concentrations of acetic acid during eight odorant trials were recorded; eight clean-air trials were also conducted. At the highest concentration, changes in respiratory behavior were observed as early as 200 ms after stimulus onset in some subjects. Inspiratory volumes during odorant presentation were lower than those seen just before stimulation. The magnitude of this decrease was directly related to the concentration of acetic acid and to the perceived intensity of the odor and degree of nasal irritation.

Airway Resistance↗
PubMed1992

Environmental tobacco smoke: current assessment and future directions.

Scientific information on environmental tobacco smoke (ETS) is critically reviewed. Key areas addressed are: differences in chemical composition between mainstream smoke, sidestream smoke, and ETS; techniques for measurement of ETS; epidemiology; in vitro and in vivo toxicology; and chamber and field studies of perceptual or physiological effects. Questions concerning estimation of ETS exposure, suitability of various biomarkers, calculation of lifetime dose, control of confounding variables, use of meta-analysis, and the relationship between ETS concentrations and human responses all emphasize the need for additional research in order to assess potential effects of ETS on health or comfort.

Animals↗
PubMed1992

Pleuropulmonary paragonimiasis in a Laotian immigrant to Australia.

A case of pleuropulmonary paragonimiasis that mimicked reactivation of pulmonary tuberculosis, pneumonia, and neoplasm occurred in a Laotian immigrant to Australia. The key to the diagnosis of this condition is awareness of the disease in persons from this region. The diagnosis was supported by enzyme-linked immunosorbent assay testing. The patient was successfully treated with praziquantel.

Aged↗
PubMed1990

Relationship of a putative receptor protein kinase from maize to the S-locus glycoproteins of Brassica.

The protein kinase family of enzymes mediates the responses of eukaryotic cells to both inter- and intracellular signals. These enzymes are either serine/threonine-specific or tyrosine-specific. Many of the latter are transmembrane receptors and are important in transduction of extracellular signals across the plasma membrane, whereas few examples of receptor serine kinases have been reported. We have now identified a complementary DNA clone from Zea mays (L.) encoding a putative serine/threonine-specific protein kinase structurally related to the receptor tyrosine kinases. This structural similarity is evidence for a previously undescribed class of transmembrane receptor in higher plants likely to be involved in signal reception and transduction. Furthermore, the catalytic domain of this protein kinase is linked through a transmembrane domain to an extracellular domain similar to that of glycoproteins encoded in the self-incompatibility locus of Brassica which are involved in the self-recognition system between pollen and stigma.

Amino Acid Sequence↗
PubMed1990

Functional properties of the anaerobic responsive element of the maize Adh1 gene.

The functional properties of the anaerobic responsive element (ARE) of the maize Adh1 gene have been analysed using a transient expression assay in electroporated maize protoplasts. The ARE functions in both orientations although inversion of the ARE sequence relative to the TATA box element produces slightly weaker promoter activity under anaerobic conditions and elevated expression under aerobic conditions. Promoter activity under anaerobic conditions is proportional to the number of complete ARE sequences in the Adh1 promoter. The ARE contains two sub-regions and dimers of sub-region II are as efficient as the wild-type sequence in activating gene expression under anaerobic conditions. However, sub-region I dimers do not appear capable of inducing gene expression in response to anaerobic stress. We conclude that sub-region II is essential for anaerobic induction of gene expression. Reporter gene expression remains constant when the spacing between sub-regions of the ARE is increased up to at least 64 bp, but increased spacing of 136 bp or greater abolishes expression in both aerobic and anaerobic conditions, indicating that a close association of the two sub-regions is required both for anaerobic responsiveness and for maximal levels of aerobic gene expression. When the ARE is placed upstream of position -90 of the CaMV 35S promoter, the ARE produces a high level of expression in both aerobic and anaerobic conditions. The general enhancement of gene expression driven by the hybrid ARE/35S promoter in aerobic conditions requires an intact sub-region II motif since mutation or deletion of sub-region II from the hybrid promoter reduces the level of expression to that observed for the truncated 35S promoter alone. In addition, mutation of the sub-region I sequences in the ARE/35S hybrid promoter does not significantly reduce expression in aerobic conditions, relative to pARE/delta 35S(-90), suggesting that sub-region I does not contribute to this general enhancer function.

Alcohol Dehydrogenase↗
PubMed1989

Mössbauer, EPR and NMR studies of the acid-induced reduction and changes in spin state of ferric bleomycin.

Iron-57 Mössbauer, electron paramagnetic resonance (EPR) and H-1 nuclear magnetic resonance (NMR) studies of iron-bleomycin complexes in the pH range from 1.0 to 6.0 are reported. Sequential protonation of the ligands produces a variety of high-spin and low-spin complexes of the metal. Of particular interest is the reversible equilibrium between Fe(III)- and oxygen-stable Fe(II)-bleomycin. Below pH 3.5 Fe(II) complexes form, with maximal reduction occurring at approximately pH 2. At still lower pH, Fe(III) complexes unassociated with bleomycin become dominant. The observed reduction in the absence of exogenous reducing agents suggests the possible involvement of intramolecular autoreduction in bleomycin-mediated DNA degradation.

Bleomycin↗
PubMed1989

Psychological consequences of blunt head trauma and relation to other indices of severity of injury.

To investigate the relationship between APACHE II, Injury Severity Score (ISS), Glasgow Coma Score (GCS), and behavioral outcome, a group of 39 patients who had been admitted on an emergency basis with a traumatic head injury were selected from the Neuropsychology Registry for study. Except for subtle personality and cognitive changes, all of the patients were making good neurological recoveries. The Halstead-Reitan Neuropsychological Test Battery, which has been shown to be accurate in identifying brain-damaged patients, was used as the measure of outcome. The age of the patients ranged from 16 to 49 years (mean, 25.6; SD, 9.3). The patients' educational levels ranged from elementary school to college (mean, 11.6 years of education; SD, 1.5). Halstead Impairment Indexes (HII) ranged from 0.0 to 1.0 (mean, 0.6; SD, 0.26). APACHE II scores were calculated using the worst values, obtained during the first 24 hours. These scores ranged from 5 to 35 (mean, 16; SD, 7). APACHE II was found to not significantly correlate with HII (r = 0.21, P greater than .05). ISS was calculated for each patient and ranged from 5 to 70 (mean, 27; SD, 13). ISS was found to significantly correlate with HII (r = 0.38, P less than .01). GCS ranged from 3 to 15 (mean, 9.3; SD, 3.4). Of all the correlations, GCS was the most strongly correlated with outcome as measured by the HII (r = -0.44, P less than .01). Our data emphasize that head-injured patients have subtle cognitive dysfunction even when apparently recovering well and demonstrate the need for formal psychological evaluation in all patients with injury significant enough to warrant hospitalization.

Adolescent↗
PubMed1989

IQ levels following trauma.

One hundred fifteen consecutive trauma patients who experienced a head injury and were administered a Wechsler Intelligence Scale as outpatients were selected for study from the Neuropsychology Registry. These patients ranged in age from 4 to 61 years. At the time of examination, all were living at home with their families. Dividing this group of patients on the basis of a Glasgow Coma Score (GCS) of 10 revealed significant differences in group mean post-traumatic IQs. The more severely injured group of patients had a mean post-traumatic IQ of 93.6; the less severely injured patients had a mean IQ of 103.5. The difference between these two groups is significant (p less than 0.005). When divided on the basis of a GCS of 13, the more severely injured group of patients had a mean post-traumatic IQ of 94.2 and the less severely injured group of patients had a mean post-traumatic IQ of 104.2. The difference between these two groups is also statistically significant (p less than 0.0005). There was no statistically significant (p greater than 0.05) difference in the mean post-traumatic IQs of these patients divided on the basis of an Injury Severity Score (ISS) of 15. However, there was a significant difference (p less than 0.05) when the patients were divided at ISS of 17. The less severely injured patients had a mean post-traumatic IQ of 101.2 and the more severely injured patients had a mean post-traumatic IQ of 95.8. The difference between these two groups is statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Proteus syndrome.

The term Proteus syndrome was coined in 1983 to describe a disorder of skeletal, hamartomatous, and other mesodermal malformations. The syndrome was named after the Greek god Proteus, whose name means "the Polymorphous." Clinical features of this new syndrome are currently being defined. Including the case reported herein, we have found 34 patients with Proteus syndrome described in the English literature. Major clinical findings, defined as those findings seen in more than half of the cases, include hemihypertrophy, macrodactyly, exostoses, epidermal nevi, characteristic cerebriform masses involving the plantar or palmar surfaces, a variety of subcutaneous masses, and scoliosis. Histologic examination of subcutaneous masses has identified a variety of lipomatous, hamartomatous, and angiomatous tumors.

Abnormalities, Multiple↗
PubMed1988

Anaerobically regulated aldolase gene of maize. A chimaeric origin?

The sequence of the anaerobically induced fructose 1,6-bisphosphate aldolase gene of maize is presented. Analysis of the upstream sequences of the aldolase gene reveals a six base-pair sequence (TGGTTT) with perfect homology to one of the sub-regions of the anaerobic regulatory element (ARE) which is responsible for the anaerobic induction of the maize alcohol dehydrogenase 1 gene (Adh1). In the aldolase gene this sequence is located at position -70 relative to the start of transcription, in a small segment proven by functional analysis to be important for expression of the aldolase gene. Since this six base-pair sequence has been shown to be critical for anaerobic induction of the Adh1 mRNA, is in the functional promoter region of aldolase and is also present in a homologous position in Adh2 (another anaerobically-induced gene), we suggest this hexanucleotide is essential for anaerobic regulation of each of these genes. The maize aldolase gene is about 50% homologous at the amino acid level to the animal aldolase gene but has a completely different intron/exon structure. While the rat aldolase gene has nine introns the maize gene has a single large intron near the N terminus of the coding region. Because there is 55% homology downstream from the intron and very little homology upstream, we suggest that the maize gene has acquired a 5' region containing signals for anaerobic regulation and fortuitously adding a new N-terminal region to the protein. We must suppose that the plant gene has lost the remaining introns.

Anaerobiosis↗
PubMed1988

Sequence and characterization of two auxin-regulated genes from soybean.

The auxin-regulated expression of two poly(A)+ mRNAs in soybean hypocotyl was demonstrated by cloning of the cDNAs and Northern blot hybridization analyses (Walker, J.C., and Key, J.L. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 7185-7189). The corresponding genes, designated Aux28 and Aux22, have been isolated, and the cDNAs and genes have been sequenced. The Aux28 and Aux22 genes are present at one to two copies per haploid genome, contain four and two introns, and encode hydrophilic proteins of 26.8 and 21.5 kDa, respectively. Although the cDNAs were isolated independently and do not cross-hybridize under stringent hybridization conditions, the protein coding sequences of the two cDNAs have several colinear regions of high homology at the nucleic acid (77-80%) and the amino acid (80-100%) levels; together these regions constitute approximately a third of the protein coding sequences of the cDNAs. These data, together with genomic Southern blot hybridization analysis and hybrid-select translations of mRNAs homologous to the cDNAs, show that these genes belong to two related multigene families. We have identified two sequences, TGATAAAAG and GGCAGCATGCA, that occur at similar distances upstream of the transcription start site in each gene, and the spacing between these two elements is essentially identical in the two genes. The possible significance of these sequences is under evaluation.

Amino Acid Sequence↗
PubMed1988

Behavioral consequences of trauma.

A group of 65 head-injured patients, making an apparent good recovery, were studied with the Halstead-Reitan neuropsychological test battery because of personality or cognitive difficulty. A significant relationship was identified between outcome as measured by the Halstead Impairment Index and both Injury Severity Score and Glasgow Coma Scale score. A significant relationship was also found to exist between the Halstead Impairment Index and employment status of the study group. Patients were placed in three groups, depending on their impairment index. Of the complications identified, spinal fracture, pupillary dysfunction, and intracranial pressure elevation were consistently associated with an impaired performance on the neuropsychological testing. These findings suggest that there is a relationship between head injury complications and neuropsychological potential which can cause lingering problems and influence the patient's rehabilitation process.

Adolescent↗
PubMed1988

Schistosoma mansoni and S. japonicum worm numbers in 129/J mice of two types and dominance of susceptibility in F1 hybrids.

In a study on the genetics of resistance to schistosomiasis in WEHI 129/J mice, susceptibility to either Schistosoma mansoni or Schistosoma japonicum was shown to be unequivocally dominant in F1 hybrid crosses between genetically resistant WEHI 129/J and susceptible BALB/c mice. The operation of only 1 or 2 genes in the expression of resistance to S. mansoni was suggested by backcross analysis. Thus, approximately 25% of (BALB/c x WEHI 129/J) F1 x WEHI 129/J mice were resistant to S. mansoni infection, whereas resistance was manifest in approximately 50% of WEHI 129/J mice. The data are consistent with resistance being controlled by 1 recessive gene having 50% penetrance. We also report that 129/J mice obtained directly from the Jackson Laboratories (Bar Harbor, Maine) (designated JAX 129/J), differ from locally bred WEHI 129/J in being entirely susceptible to S. mansoni infection. However, both WEHI 129/J and JAX 129/J are relatively resistant to S. japonicum infection.

Animals↗
PubMed1986

Olfactory and nonolfactory odor detection in pigeons: elucidation by a cardiac acceleration paradigm.

A technique for the Pavlovian conditioning of cardiac acceleration in response to odorants was developed and used to compare the sensitivity of pigeons to four odorants before and after resection of the olfactory nerves. This method provided quite reliable psychophysical functions yet required relatively little training time. Thresholds of normal pigeons to n-amyl acetate, n-butyl acetate, benzaldehyde and butanol were approximately 10(-4), 10(-5), 10(-3.3) and 10(-4.3) of vapor saturation, respectively. Following resection surgery, sensitivity decreased by 2 to 4 log units. When transection of the ophthalmic branch of the trigeminal nerve was combined with olfactory nerve resection, little evidence of a further decline in odor sensitivity was seen. Based on these results each of these compounds could be used, at concentrations below the postoperative threshold, to study, in isolation, both normal and reconstituting olfactory systems in the pigeon.

Animals↗