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Biomedical subjects

T E Jones

Publications and source records attributed to T E Jones.

At least 37 records · Page 2Linked to original sources
PubMed1994

Doubly labeled water measurement of human energy expenditure during exercise at high altitude.

Estimates of total daily energy expenditure (TDEE) by the doubly labeled water (DLW, 2H(2)18O) and intake balance (I-B) methods were compared in six male soldiers studied over 6 days that included 5 days of strenuous winter exercise at 2,500- to 3,100-m elevation. Use of body energy stores [-9.54 +/- 1.54 (SD) MJ/day or -2,280 +/- 368 kcal/day] was estimated from changes in body weight, body density (hydrodensitometry), and total body water (H(2)18O dilution). The subjects wore computerized activity monitors and kept daily records of ration consumption (9.87 +/- 3.60 MJ/day or 2,359 +/- 860 kcal/day). Accuracy of individual DLW and I-B TDEE values was estimated from the correlations of TDEE with fat-free mass (FFM) or total weight (body wt + load). The DLW and I-B estimates of TDEE differed by -12.0 to 15.2% but provided comparable estimates of group mean TDEE (DLW = 19.07 +/- 2.37 MJ/day or 4,558 +/- 566 kcal/day; I-B = 19.41 +/- 3.72 MJ/day or 4,639 +/- 889 kcal/day; P > 0.05). The DLW TDEE was correlated with both FFM (r2 = 0.89, P < 0.01, power = 0.95) and total weight (r2 = 0.95, P < 0.01, power = 0.99), whereas I-B TDEE was correlated only with total weight (r2 = 0.75, P < 0.03, power = 0.81). Under adverse field conditions the DLW method provided individual TDEE estimates that were probably more accurate than those provided by the I-B method.

Activity Cycles↗
PubMed1994

Relationship between resistance of salmonids to furunculosis and recovery of Aeromonas salmonicida from external mucus.

Fish were sampled at the Ed Weed State Fish Hatchery (South Hero, Vermont, USA) in September 1992. Aeromonas salmonicida was common, with concentrations as high as 10(5) to 10(7) colony-forming units per gram of mucus, and readily recovered from most mucus samples obtained from furunculosis-sensitive populations of brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and Atlantic salmon (Salmo salar). The pathogen was the predominant microorganism and accounted for greater than 85% of the total number of bacteria isolated from the mucus of these fish. By comparison, A. salmonicida was recovered only from two rainbow trout (Oncorhynchus mykiss), and bacterial frequencies did not exceed 10(3) colony-forming units per gram of mucus. The pathogen was not recovered from the mucus of steelhead (O. mykiss) or Rome brown trout (Salmo trutta) selectively bred for resistance to furunculosis, even though there was widespread contagion throughout the hatchery and fish were cultured on a common, unprotected water supply.

Aeromonas↗
PubMed1992

Dopamine receptor antagonists increase markedly the quantity of retrograde transport of HRP in the rat masseteric motoneuron.

Horseradish peroxidase (HRP) was injected, bilaterally, into the rat masseter muscle, subsequent to an intramuscular or intraperitoneal injection of one of five dopamine antagonists (chlorpromazine and haloperidol as the D1 and D2 receptor antagonist, SCH 23390 as the specific D1 receptor antagonist, sulpiride and domperidone as the specific D2 receptor antagonist). Control rats received an injection of a corresponding vehicle solution. After a survival period of 16 h, the brainstem was cut into 60 microns cryosections and processed with the TMB technique. The amount of retrogradely transported HRP was quantitatively measured in terms of the amount of HRP reaction product present in the motoneuron by the method which we have developed using an image processing system combined with a light microscope and a TV camera. Chlorpromazine, haloperidol, SCH 23390 and sulpiride significantly raised the quantity of retrograde transport of HRP. On the contrary, domperidone which can not penetrate the blood-brain barrier showed no significant change in the amount of the retrograde transport. In addition, an intravenous injection of chlorpromazine (8 mg/kg) was found to increase the amplitude of monosynaptic masseteric reflex EMG activity evoked by stimulations of the mesencephalic trigeminal nucleus. These results suggest that a possible regulatory system involving the dopamine receptor in the uptake and retrograde transport of HRP from axon terminals to cell bodies of the masseteric motoneuron exists in higher order neurons which make synaptic contact with the motoneuron.

Animals↗
PubMed1992

The differentiation of the skin and its appendages. I. Normal development of papillary ridges.

In the present study, the normal development of papillary ridges was studied in the volar pads of both fore and hindpaws of the opossum, Monodelphis domesticus. At birth, the developmental state of the opossum's paws is equivalent to that of a six-week human embryo. The development of papillary ridges in the opossum occurs entirely postnatally and the hindpaw lags behind the forepaw by at least four days in most developmental parameters. Papillary ridge formation is preceded by four events: skin innervation, Merkel cell differentiation, mesenchymal condensation, and epidermal proliferation. The apical pads at the tips of the digits and the interdigital pads between the heads of the metacarpals (or metatarsals) have a unique pattern of innervation and mesenchymal content as compared to the non-pad skin. Each pad is innervated by a prominent nerve trunk and axons ascend towards the epidermis providing a density of innervation that exceeds that in the non-pad epidermis. Merkel cells are absent in non-pad epidermis but present in the pads prior to the onset of formation of papillary ridges. A loose aggregation of mesenchyme forms the core of the pads and the superficial dermis is more cellular in the pads as compared to the equivalent dermis in surrounding non-pad skin. Developing papillary ridges always contained Merkel cell-axon complexes. Merkel cell axon complexes serve as the anatomical substrate of slowly adapting (SA) mechanoreceptors. The presence of these complexes during early skin differentiation is consistent with the use of the opossum's forepaw in climbing to the nipple, but also suggests other possible functions. We hypothesize that the nervous system might play a role in the timing or patterning of the formation of papillary ridges.

Animals↗
PubMed1992

The differentiation of the skin and its appendages. II. Altered development of papillary ridges following neuralectomy.

In order to test the hypothesis that the nervous system is an important determinant of skin differentiation, deletions of the left lumbosacral dorsal root ganglia (DRGs), the sources of cutaneous afferents to the left hindpaw, were performed on opossum pups at day 1 when hindpaws have just begun to be innervated. At birth, each lumbosacral DRG measures about 200 microns rostrocaudally and a deletion measuring 1 mm would span 4-5 DRGs. Following survival periods of 5-24 days, serial sections through the trunk documented partial left lumbosacral DRG deletion and a variable degree of spinal cord destruction. The blood supply to the trunk and hindpaws was preserved. Bilateral enlargement of residual DRGs was observed and regenerating skin at the site of the deletion was hyperplastic and hyperinnervated. The skin of the plantar pads of the hindpaws was studied following the neuralectomies. Statistically significant differences were observed between the left (experimental) and right (control) hindpaws. The density of innervation of the left hindpaw was reduced compared to the right hindpaw, development of papillary ridges was retarded by 3-4 days, and non-innervated Merkel cells were hypogranulated. This period of delay in ridge development is probably a reflection of the expansion of residual DRGs into the peripheral domains of deleted DRGs. The present study confirms a role for afferent nerves in the timing of cutaneous differentiation and a mutual trophic dependence between cutaneous nerves and Merkel cells in the epidermis.

Animals↗
PubMed1991

Doubly labeled water measurement of human energy expenditure during strenuous exercise.

The energy expenditures (EE) of 23 adult male Marines were measured during a strenuous 11-day cold-weather field exercise at 2,200- to 2,550-m elevation by both doubly labeled water (2H2 18O, DLW) and intake balance methods. The DLW EE calculations were corrected for changes in baseline isotopic abundances in a control group that did not receive 2H2 18O. Intake balance EE was estimated from the change in body energy stores and food intake. Body energy-store changes were calculated from anthropometric [-1,574 +/- 144 (SE) kcal/day] and isotope dilution (-1,872 +/- 293 kcal/day) measurements made before and after the field exercise. The subjects kept daily logbook records of ration consumption (3,132 +/- 165 kcal/day). Mean DLW EE (4,919 +/- 190 kcal/day) did not differ significantly from intake balance EE estimated from food intake and either anthropometric (4,705 +/- 181 kcal/day) or isotope dilution (5,004 +/- 240 kcal/day) estimates of the change in body energy stores. The DLW method can be used with at least the same degree of confidence as the intake balance method to measure the EE of active free-living humans.

Adult↗
PubMed1990

Yield loss assessments for cultivars of broccoli, lettuce, and onion exposed to ozone.

The effects of the photochemical oxidant air pollutant ozone (O(3)) on growth and yield of three garden crops, broccoli (Brassica oleracea L.), lettuce (Lactuca sativa L.), and onion (Allium cepa L.) were studied in an open-top chamber experiment conducted in the field in southern California. Four cultivars each of leaf lettuce, broccoli, and globe onion were exposed to charcoal-filtered air (CF), non-filtered (NF) air, or NF plus 1.5 times ambient O(3) concentration from 4 weeks after germination in January or February until harvest. Exposures lasted 31 days for lettuce, 55 to 78 days for broccoli, and 105 days for onion. Results showed that despite severe O(3) injury to outer leaves, lettuce yields were not affected by O(3). Broccoli also was resistant to O(3) and no growth reduction was observed at ambient O(3) concentrations. Onions were more susceptible to O(3), but only one cv. 'Rio Bravo' had significant yield losses (ca. 5%) at ambient O(3) levels. These results suggest that, in general, concentrations of O(3) in the winter and spring may be below the threshold for adverse effects on yields of broccoli, lettuce and onion.

Journal Article↗
PubMed1989

Innervation of the tooth pulp by the mesencephalic trigeminal nucleus in the cat: a retrograde horseradish peroxidase study.

HRP was applied to the tooth pulp of 8 cats. Six were subjected to postoperative administration of the anti-inflammatory drug, prednisolone, whereas the remaining two were not. In all prednisolone-treated cats, labeled neurons were found in both the mesencephalic trigeminal nucleus and trigeminal ganglion, ipsilaterally. On the other hand, no labeled neurons were observed in the mesencephalic nucleus in cats receiving no steroid.

Animals↗
PubMed1989

The morphogenesis of the posterior neural tube and tail in Monodelphis domesticus.

The process of secondary neuralation has been studied in the Brazilian opossum, Monodelphis domesticus. Secondary neuralation in this mammal was found to have qualities of secondary neuralation that were present in both the chick and the mouse. In this study, four stages of secondary neuralation were found beginning with the medullary cord stage. Other stages in the differentiation of the secondary neural tube were: differentiation of the neuroepithelium, cavitation of the medullary cord, and proliferation of the neural tube. The process of secondary neuralation proceeded in a rostral-to-caudal direction and was found to be independent of age. Diastematomyelia (doubling of the tube) was found in several animals. The process of cavitation was completed by the joining of several small, focal cavities in a rostral-to-caudal direction. The most distinctive feature of secondary neuralation in this animal was the finding of axons within the secondary neural tube, a feature not characteristic of either the chick or the mouse.

Animals↗
PubMed1987

Neural modulation of cutaneous differentiation: epidermal hyperplasia and precocious hair development following partial neuralectomy in opossum pups.

The original intent of the present study was to evaluate the compensatory response of the nervous system to areas of denervation. A portion of the spinal cord in the lumbosacral region of one-day opossum pups (Monodelphis domesticus) was removed by cauterization. This partial neuralectomy produced an expected compensatory response of neurons in the dorsal root ganglia, but in addition produced unexpected abnormalities of cutaneous differentiation. At 4-6 days following surgery, an increase in the thickness of the epidermis resembling glabrous palmar or plantar skin was seen. This hyperplastic epidermis appeared to be associated with an abnormally dense innervation of the dermis and epidermis. Eight days following partial neuralectomy most animals showed areas of precocious hair development. Nerve fibers were always seen in the dermis associated with these precocious hairs and were seen to penetrate the basal lamina in the region of the epidermal-hair shaft boundary. These results imply a critical role for afferent nerves in the normal development of the skin and its appendages.

Animals↗
PubMed1985

Herpes simplex type 1 ribonucleotide reductase. Mechanism studies with inhibitors.

Several known inhibitors of mammalian ribonucleotide reductase were studied for their interactions with herpes simplex virus type 1 (HSV-1) ribonucleotide reductase. MAIQ (4-methyl-5-amino-1-formylisoquinoline thiosemicarbazone) produced apparent inactivation of HSV-1 ribonucleotide reductase. Only catalytically cycling, not resting, enzyme could be inactivated. Double reciprocal replots of the rates of inactivation versus the concentration of MAIQ indicated that a reversible complex with the enzyme was formed prior to inactivation. In the presence of 10 microM CDP, the maximum rate of inactivation was 20 per h (t1/2 = 3 min). The half-maximum rate was achieved at about 15 microM MAIQ. INOX (periodate-oxidized inosine) also appeared to inactivate HSV-1 ribonucleotide reductase. In contrast to MAIQ, it readily inactivated resting as well as cycling enzyme. CDP retarded the rates of inactivation by INOX. An initial reversible complex between INOX and enzyme was not detectable under the conditions used. IMPY (2,3-dihydro-1H-pyrazolo(2,3-a)imidazole) and guanazole (3,5-diamino-1,2,4-triazole) produced reversible inhibition. Although the data with both inhibitors were most consistent with the noncompetitive inhibition model (versus CDP), the data with guanazole were also marginally consistent with the uncompetitive model.

Guanazole↗
PubMed1985

Moxalactam kinetics during continuous ambulatory peritoneal dialysis after intraperitoneal administration.

Moxalactam kinetics during continuous ambulatory peritoneal dialysis (CAPD) was followed in eight patients after a single intraperitoneal dose of 1 g. Approximately 60% of the dose was absorbed after a dwell time of 4 h. Dialysis solutions were exchanged at 4-h intervals with an overnight dwell of 8 h. The mean (+/- standard deviation) elimination half-life was 13.2 +/- 2.9 h, and the mean apparent volume of distribution was 0.22 +/- 0.08 liters/kg. Mean total clearance was 11.5 +/- 2.4 ml/min, with a mean dialysis clearance of 2.3 +/- 0.5 ml/min. The maximum concentration in plasma ranged from 24.5 to 54.1 micrograms/ml. Moxalactam concentrations in the peritoneal dialysis fluid were above 80 micrograms/ml during the first exchange and above 2 micrograms/ml for a further three exchanges. A suggested intraperitoneal dose regimen for patients undergoing CAPD is 1 g initially, followed by 15 to 25% of the recommended dose for normal patients given at the same time intervals, or 30 to 50% of the recommended dose at twice the usual intervals. Moxalactam is suggested for initial treatment of peritonitis in CAPD patients who do not have ready access to the antibiotic of choice.

Adult↗
PubMed1985

Early differentiation of the afferent nervous system in glabrous snout skin of the opossum (Monodelphis domesticus).

Early differentiation of afferent fibers innervating the snout skin of Monodelphis domesticus was studied by electron microscopy and by light-microscopic silver staining techniques. This study was undertaken to investigate the relationship between dermal and epidermal innervation in the neonate opossum while correlating these findings with behavioral responses. The advantage of using this species is that the neonate is born in a very immature stage and has a rostrocaudal development of the peripheral nervous system. Glabrous snout skin from young opossums was studied at birth (0 day) and postnatal days 1, 3, and 5. Neurite bundles were seen within the dermis, with axons and growth cones approaching the epidermis. Some axons penetrated the dermal-epidermal junction in newborn pups. Merkel cells were consistently numerous during the time spanned by this study. Mature Merkel cells had granules polarized toward an associated neurite and were often located in the base of the rete pegs. Immature Merkel cells were characterized by a lack of polarization of granules and absence of an apposed neurite, suggesting that these cells can differentiate without an associated neurite. Contiguous Merkel cells had junctional complexes in 0- and 1-day animals. Schwann cells, identified by their contact with neurite bundles, were present in large numbers, especially in the superficial dermis. Melanocytes could be identified in the epidermis in 5-day pups only. Developing rete pegs could be recognized in 0-day animals and became prominent in 5-day pups. These observations suggest that afferent fibers are present at a very early age and that some of these fibers are anatomically mature. These findings support the concept that the ability of the neonate to locate a teat and suckle requires only the presence of mature epidermal innervation, while dermal receptors appear later during postpartum development.

Afferent Pathways↗
PubMed1984

Monophosphates of formycin B and allopurinol riboside. Interactions with leishmanial and mammalian succino-AMP synthetase and GMP reductase.

Formycin B 5'-monophosphate (Form B-MP) and allopurinol riboside 5'-monophosphate ( HPPR -MP) are isomers of IMP that are metabolically produced when Leishmania spp. are incubated with the antileishmanial agents formycin B and allopurinol or allopurinol riboside. The interactions of Form B-MP with succino -AMP synthetase and GMP reductase from both leishmanial and mammalian sources were compared with the data of earlier studies with HPPR -MP. Both analogs could substitute for IMP as a substrate for succino -AMP synthetase isolated from Leishmania donovani. The V'max values of Form B-MP and HPPR -MP were about 1% of the V'max of IMP. Only Form B-MP (and not HPPR -MP) could serve as an alternative substrate for mammalian succino -AMP synthetase. The V'max of Form B-MP was 40% that of IMP. The corresponding analogs of AMP, ADP and ATP were produced when Formycin B was incubated with mouse L cells. The Formycin A residue was incorporated into the cellular RNA. The amount of Formycin A-TP produced (relative to ATP) in mouse L cells was considerably less than that produced in Leishmania spp. Both Form B-MP and HPPR -MP were inhibitors of partially purified GMP reductase from L. donovani. The binding of Form B-MP and HPPR -MP to human GMP reductase was 40- and 100-fold weaker, respectively, than the binding to leishmanial GMP reductase. Pretreatment of promastigotes of L. donovani with either allopurinol or Formycin B resulted in greater than 95% reduction of the incorporation of the radiolabel from [14C]xanthine into ATP and greater than 80% reduction of the incorporation of the label into GTP. The HPPR -MP and Form B-MP present in these cells may have inhibited the leishmanial succino -AMP synthetase and GMP reductase. The analogs had little or no effect on the pool sizes of ATP and GTP of either mouse L cells or L. donovani.

Adenylosuccinate Synthase↗
PubMed1984

Simultaneous demonstration of neuronal somata that innervate the tooth pulp and adjacent periodontal tissues, using two retrogradely transported anatomic markers.

Two axonally transported substances were used to demonstrate the spatial relationships between trigeminal ganglion cells innervating the tooth pulp and adjacent periodontal tissues of the mandibular canine teeth in cats. 4',6-Diamidino-2-phenylindole (DAPI) and horseradish peroxidase (HRP) were applied in the periodontal tissues and in the tooth pulp, respectively. The trigeminal ganglion and brain stem were then examined for the presence of fluorescent DAPI-labeled cells, HRP-labeled cells, and cells containing both labels. Cells containing either DAPI or HRP were observed in the mandibular portion of the ganglion; DAPI-labeled cells were observed in the pontine portion of the mesencephalic nucleus of the trigeminal nerve. Examples of double labeling, indicative of collateralization of single neurons to innervate both the tooth pulp and adjacent tissues, were not commonly observed. Finally, there was no indication of a mesencephalic nucleus contribution to the tooth pulp innervation.

Animals↗
PubMed1983

Conversion of 2,6-diamino-9-(2-hydroxyethoxymethyl)purine to acyclovir as catalyzed by adenosine deaminase.

Adenosine deaminase (ADA) was partially purified from several sources using affinity chromatography. These enzymes have the capacity to catalyze the deamination of 2,6-diamino-9-(2-hydroxyethoxymethyl)purine (A134U) to form the antiviral agent acyclovir [9-(2-hydroxyethoxymethyl)guanine]. Their relative substrate efficiencies (Vmax/Km) with A134U (standardized to adenosine = 100) were: dog ADA, 0.092; human ADA, 0.015-0.029; rat ADA, 0.025; calf ADA, 0.016; and Escherichia coli ADA, 0.0003. In addition to having the lowest efficiency with A134U, the bacterial ADA was also distinguished by its lack of binding of the mammalian ADA inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine and by its weak binding to the 9-(p-aminobenzyl)adenine-agarose affinity column. Four minor metabolites of A134U and acyclovir have been reported to be produced in the rat. These compounds are oxidized on either the C-8 position of the ring or the terminal carbon of the side chain. Neither acyclovir nor any of these metabolites produced significant inhibition of calf intestine ADA. The oxidized metabolites containing an N-6 amino group were extremely slow substrates of this enzyme.

Acyclovir↗