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T Hayes

Publications and source records attributed to T Hayes.

At least 19 recordsLinked to original sources
PubMed1997

A neurohormone regulating both methyl farnesoate synthesis and glucose metabolism in a crustacean.

Methyl farnesoate (MF) has been identified as a juvenile hormone-like compound in crustacea which has central roles in the regulation of development and reproduction. To study the regulation of MF synthesis, we isolated a neuropeptide which inhibits MF synthesis from the neurohemal organ-sinus gland X-organ complex of the spider crab Libinia emarginata. The primary structure of this neuropeptide has been determined. It has 72 amino acid residues (deduced molecular mass 8490.5 Da) with pyroglutamic acid at the N-terminus and NH3 at the C-terminus. It shares a high percentage of sequence identity with other sinus gland neuropeptids which form the unique family of CHH neuropeptides of crustacea. Activity studies showed that this neurohormone has dual effects: it inhibited MF synthesis in vitro and had hyperglycemic activity when injected into crabs.

Amino Acid Sequence↗
PubMed1996

Allele-specific hybridization of lipoprotein lipase and factor-V Leiden missense mutations with direct label alkaline phosphatase-conjugated oligonucleotide probes.

Direct label alkaline phosphatase (AP) conjugated oligonucleotide probes (AP-DNA) were prepared to assess their utility for allele-specific detection of single base substitutions. Oligonucleotide conjugates were designed to detect point mutations in the genes for lipoprotein lipase (LPL) and coagulation factor-V (FV). Genomic DNA samples, including ones known to harbor point mutations in the genes for LPL and FV, were prepared from whole blood and subjected to polymerase chain reaction (PCR). PCR products were analyzed by Southern hybridization with the allele-specific AP-DNA probes and restriction endonuclease analysis. Thermal profiles for hybridization indicate optimal allele-specific selectivity was achieved with temperatures ranging from 45 degrees C to 55 degrees C at a total Na divided by concentration of 150 mM. Under these conditions the base changes studied were easily discriminated with allele specific hybridization signals in excess of 200:1 as estimated by scanning densitometry. Complete concordance was observed between hybridization and restriction analyses for 175 LPL and 201 FV clinical and reference samples. The total time for analysis of the PCR products was less than 2 h with a dot blot hybridization protocol.

Alkaline Phosphatase↗
PubMed1996

Two novel thioesterases are key determinants of the bimodal distribution of acyl chain length of Cuphea palustris seed oil.

The seed oil of Cuphea palustris has an unusual fatty-acyl composition, whereby the principal fatty-acyl groups, myristate (64%) and caprylate (20%), differ by more than two methylenes. We have isolated two thioesterase (TE) cDNAs from C. palustris, encoding proteins designated Cp FatB1 and Cp FatB2, which, when expressed in Escherichia coli, have TE activities specific for 8:0/10:0- and 14:0/16:0-acyl carrier protein substrates, respectively. The specific activities of the recombinant affinity-purified enzymes indicate that Cp FatB2 is kinetically superior to Cp FatB1. This result is consistent with the predominance of 14:0 in the seed oil, despite apparently equal mRNA abundance of the two transcripts in the seed. In C. palustris the expression of both sequences is confined to the seed tissues. Based on these findings we propose that these two enzymes are major factors determining the bimodal chain-length composition of C. palustris oil. Analysis of the immature and mature seed oil by reverse-phase high-performance liquid chromatography confirmed that the principal triglycerides contain both 8:0 and 14:0. This result indicates that both fatty acids are synthesized at the same time and in the same cells at all developmental stages during oil deposition, suggesting that the two TEs act together in the same fatty acid synthesis system.

Amino Acid Sequence↗
PubMed1996

Leucokinin increases paracellular permeability in insect Malpighian tubules

There are two major transport pathways across epithelia: a transcellular pathway through cells and a paracellular pathway between cells. Previous electrophysiological studies in mosquito Malpighian tubules suggested that the neuropeptide leucokinin-VIII (LK-VIII) increases the chloride permeability of the paracellular pathway. To test the effect of LK-VIII on the paracellular pathway further, we measured transepithelial permeabilities of inulin and sucrose in isolated Malpighian tubules from the mosquito Aedes aegypti. Cell membranes are impermeable to inulin and sucrose, leaving the paracellular pathway as the only route for their transepithelial permeation. LK-VIII (10(-6) mol l-1) significantly increased transepithelial permeability to both inulin (by 73.8 %) and sucrose (by 32.4 %) in parallel with a significant increase in rates of transepithelial fluid secretion (by 75­90 %). Cyclic adenosine monophosphate (cyclic AMP, 10(-4) mol l-1), which is known to stimulate transcellular transport, also increased rates of transepithelial fluid secretion (by 57­59 %), but it did so without increasing the permeability to sucrose and inulin. Thus, LK-VIII increases the permeability of the paracellular pathway whereas cyclic AMP does not.

Journal Article↗
PubMed1996

The Telemedicine Information Exchange (TIE).

An on-line information service, the Telemedicine Information Exchange (TIE), was established to provide a comprehensive source of telemedicine information. The TIE comprised a number of frequently updated, searchable, linked databases, each dealing with an important aspect of telemedicine. These included an extensive bibliography on telemedicine consisting of more than 2000 citations, many with abstracts. There was also a series of topical sections describing current telemedicine projects, products and services, legislation, funding, research activities, and news in the field. The TIE was designed to exploit the features of electronic information storage: hypertext linking between related pieces of information; specialized views (technical, legal, and business) of the bibliographic database; and usage monitoring to determine which data were most frequently accessed and therefore where any enhancement should be done. The TIE was made available via the World Wide Web, by remote telnet access over the Internet, and via modern. The rapid increase in the usage of the TIE since its introduction in April 1995 indicated that the TIE satisfied a need in the telemedicine community.

Computer Communication Networks↗
PubMed1995

Evidence for the hormonal function of a CRF-related diuretic peptide (Locusta-DP) in Locusta migratoria

Locusta-DP is a corticotropin-releasing factor (CRF)-related diuretic peptide isolated from the migratory locust Locusta migratoria. At nanomolar concentrations, synthetic Locusta-DP stimulated fluid secretion and cyclic AMP production by Malpighian tubules isolated in vitro and increased the rate of amaranth clearance in starved locusts to levels comparable with those observed during post-feeding diuresis. The peptide also caused a marked (approximately 10 %), but short-lived, reduction in the haemolymph volume of starved locusts. A polyclonal antiserum raised against Locusta-DP(29-46) was shown to block peptidergic signal transfer in vitro and in vivo. Pre-treatment of Locusta-DP (5 nmol l-1) with antiserum diluted 1:100 resulted in a rapid reduction in the free peptide concentration to less than 1 nmol l-1, the threshold for a measurable effect on cyclic AMP production by isolated tubules. In intact insects, passive immunization with Locusta-DP antiserum blocked increases in the rate of amaranth clearance in response to exogenous diuretic peptide or in response to feeding. The latter was due specifically to the binding of Locusta-DP, because when the relevant antibodies were preadsorbed with Locusta-DP(29-46), the antiserum had no effect on amaranth clearance by recently fed insects. This provides unequivocal evidence of a hormonal function for Locusta-DP in the control of primary urine production.

Journal Article↗
PubMed1994

HIV-related deaths from selected infectious diseases among persons without AIDS in New Jersey.

This study sought to quantify HIV-related deaths among persons not classified as having AIDS, in an area where AIDS incidence among injecting drug users (IDUs) is high. Death certificates of persons who were aged 25-44 years at death, died in 1987 in two New Jersey counties, and had certain infectious conditions were compared with names in the AIDS Registry. Hospital and/or Medical Examiner records were reviewed for nonmatching cases. Cases were considered as confirmed HIV infection if there was laboratory evidence of such infection and as suggestive HIV infection if the decedent had oral thrush or a combination of certain other clinical findings were present. Of 412 deaths meeting the above criteria, 165 (40.0%) were in the AIDS Registry. We investigated 205 of the remainder; of these, 7.3% were found to have AIDS, 21.5% had confirmed HIV infection without AIDS, and 15.1% had suggestive HIV infection. This increased the HIV-related mortality in excess of deaths due to AIDS in this age group by 9.2% for confirmed HIV infections and 15.6% for both confirmed and suggestive HIV infections, with deaths among IDUs increasing 12.3% for confirmed HIV infections and 18.9% for both confirmed and suggestive HIV infections. Thus, in addition to AIDS indicator diseases, a variety of other infectious conditions can lead to death in HIV-infected persons, particularly in IDUs; however, the extent of such deaths may be less than previously described.

Adult↗
PubMed1993

Interactions of temperature and steroids on larval growth, development, and metamorphosis in a toad (Bufo boreas).

The effects of temperature and steroids [testosterone (T), estradiol (E2), and corticosterone (B)] on premetamorphic growth and development were investigated in the toad (Bufo boreas). The effects of steroids were both temperature and age dependent. In the first experiment, steroids (1.1-1.4 microM) were administered by dissolving them in the water beginning 1 day after hatching at 22 degrees C or 27 degrees C. At 22 degrees C, B inhibited growth (P < 0.001) but had no significant effect on development. Forelegs never emerged in B-treated animals and all died before complete tail resorption. Discontinuation of B treatment allowed normal growth and metamorphosis, but the resulting post-metamorphic animals were significantly shorter (snout-vent length, P < 0.001) than after other treatments. At 22 degrees C, T and E2 had no effect on larval growth and development or size at metamorphosis (P > 0.05), but T induced early foreleg emergence (FLE) (P < 0.005). At 27 degrees C, B was fatal after 2 weeks of treatment, and T and E2 inhibited growth (P < 0.001) and development (P < 0.001), but did not affect time to FLE. In a second experiment at 27 degrees C, treatment with 1.1 microM B starting 15 days after hatching induced early metamorphic events (P < 0.001), such as tail resorption and emergence of the left foreleg (but not the right), but jaw and head restructuring failed to occur. All B-treated animals died before complete tail resorption. In a third experiment, 0.275 and 1.11 microM B, starting at day 43 (stage 43), induced early FLE (P < 0.05) and decreased snout-vent length at tail resorption (P < 0.005) without a dose effect. A higher dose of B (4.44 microM) decreased snout-vent length at tail resorption and time to FLE (P < 0.05) but did not affect body weight at metamorphosis (P > 0.05). Animals in this experiment survived to complete tail resorption and transformed normally. The actions of B in these experiments closely resemble those observed with administration of thyroid hormones, suggesting that steroids may interact with endogenous thyroid hormones.

Animals↗
PubMed1990

Mechanisms regulating cell number and type in the mammalian central nervous system.

In the developing brain, neurons are derived from multipotential precursor cells in a precise sequence, where the time when a neuron becomes postmitotic is closely linked to the differentiated function of the neuron. Work from our group (1) identifies the Nes+ neuronal precursor state, (2) defines growth factors that regulate the proliferation of Nes+ precursor cells and their differentiation into neurons, and (3) establishes immortal cell lines that may be useful models for the terminal differentiation of Nes+ cells into neurons and astrocytes. These results suggest that the basic technical requirements are now in place to define the signals that control the transition from a precursor cell to a postmitotic neuron in the mammalian CNS. Control of this terminal differentiation is a key step in generating the large numbers and types of cells in the CNS.

Animals↗
PubMed1989

Development and decay of systemic thermotolerance in rats.

The development and decay of thermotolerance to the lethal effect of systemic hyperthermia was investigated in Sprague-Dawley rats. Systemic hyperthermia was induced by partial submersion of gas-anesthetized rats into a temperature-controlled water bath. Survival was determined in rats challenged for periods of 10 to 90 min at 42.5 C, 24 to 144 h after a sublethal conditioning exposure of 41.8 C for 1 h. Survival curves of various exposure times at 42.5 C lethal to 50% of the animals (LD50) were determined for the conditioned animals and compared with those obtained for simultaneously treated control (unconditioned) rats. The thermotolerance ratios (TTR-LD50 for conditioned animals at various times after sublethal conditioning exposure divided by the LD50 for the control animals) were calculated and compared with the ratios reported in the literature for cells heated in vitro and for tissues heated locally in vivo. Pretreatment of rats at 41.8 C for 1 h resulted in an increase in the LD50 when rats were challenged 24 to 96 h later, with a maximum increased noted at 48 h (56.5 vs. 25.0 min for control; TTR = 2.3). The animals remained relatively resistant to the second heat treatment at 96 h and returned to control levels of heat sensitivity by 120 h. The development and kinetics of thermotolerance to lethality induced by whole-body hyperthermia need to be considered when multiple-fraction hyperthermia treatment plans are designed.

Adaptation, Physiological↗
PubMed1988

An outbreak of acute histoplasmosis in a family.

Acute pulmonary histoplasmosis was diagnosed in three members of a New Mexico family that had recently attended a family reunion in Iowa. The treating physicians rapidly documented an outbreak of atypical pneumonia in the family. The clinical features and epidemiology of the outbreak suggest histoplasmosis was contracted during exposure in an abandoned barn. Fever, chills and myalgia were the most common symptoms; shortness of breath occurred frequently.

Adolescent↗
PubMed1986

Recognition of positive and negative bandpass-filtered images.

A study is reported in which the significance for vision of low- and high-spatial-frequency components of photographic positive and negative images was investigated by measuring recognition of bandpass-filtered photographs of faces. The results show that a 1.5 octave bandpass-filtered image contains sufficient visual information for good recognition performance, provided the filter is centred close to 20 cycles facewidth-1. At low spatial frequencies negatives are more difficult to recognize than positives, but at high spatial frequencies there is no difference in recognition, implying that it is the low-frequency components of negatives which present difficulties for the visual system.

Color Perception↗
PubMed1984

Production of systemic hyperthermia in the rat.

The design of clinical trials employing whole-body hyperthermia in cancer therapy has been hampered due to lack of a suitable animal model. We describe a technique for reproducibly and efficiently inducing whole-body hyperthermia in Sprague-Dawley rats, using halothane and oxygen anesthesia and immersion in a hot water bath. Core body temperatures of between 41.5 and 43 degrees C were induced and maintained for periods of up to 200 min and survival curves were determined. The time of exposure at a given temperature that resulted in death in 50% of the animals within 24 hr after heating (LD50/24 hr) was calculated by linear logistic regression analysis. LD50 24 hr values of 115, 61, 57, 25 and 16 min were obtained for temperatures of 41.75, 42.0, 42.25, 42.5 and 42.75 degrees C respectively. This heating technique is compared to several more toxic methods for inducing whole-body hyperthermia with respect to possible pharmacological and physiological differences.

Anesthesia, Inhalation↗
PubMed1984

Potential synthetic codeine substitutes: (-)-3-O-aryl-N-methylmorphinans.

A series of novel O-aryl-N-methylmorphinans (7-19) were synthesized by the Ullmann reaction from levorphanol (4) in our search for a synthetic codeine (2) substitute with reduced addition liability. The compounds were evaluated for antinociceptive potency and receptor binding affinity. Among these compounds, (-)-3-phenoxy-N-methylmorphinan (7) is an orally active analgesic comparable in potency to codeine (2), which exhibits decreased physical dependence liability and longer duration of action.

Animals↗