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D W Johnson

Publications and source records attributed to D W Johnson.

At least 145 records · Page 8Linked to original sources
PubMed1993

A synthetic opioid peptide increases plasma growth hormone and prolactin in Holstein calves.

The effect of the synthetic opioid agonist D-Ala2,N-Me-Phe4,Met(O)5-ol enkephalin (DAMME) on plasma growth hormone (GH) and prolactin (PRL) concentrations in Holstein heifer calves was investigated in this study. The possible site of action of DAMME was determined by pretreating calves with an opioid antagonist that crosses the blood-brain barrier poorly if at all (N-methyl levallorphan-methane sulphonate [MLM]) or one that crosses readily (naloxone [NAL]). All calves were assigned to one of three treatment groups: 1) pretreatment with saline, 2) pretreatment with NAL, or 3) pretreatment with MLM. All groups were injected with DAMME 30 min after pretreatments. Plasma PRL increased after injection of DAMME in calves pretreated with saline. Prolactin concentrations were not different before and after injection of DAMME in calves pretreated with either NAL or MLM. Plasma GH increased after injection of DAMME in saline- and MLM-pretreated calves but was unchanged in NAL-pretreated calves. These data show that peripherally administered DAMME increases plasma GH and PRL in Holstein heifer calves and suggest that DAMME mediates GH release through receptors located somewhere inside the blood-brain barrier, but it can induce PRL secretion at a site located outside the barrier.

Animals↗
PubMed1993

Increased stroke risk predicted by compromised cerebral blood flow reactivity.

The authors sought to determine risk for stroke in individuals with symptomatic carotid stenosis or occlusion based upon an assessment of cerebral blood flow (CBF) reserves. Vascular reserve was assessed by two consecutive xenon/computerized tomography (Xe/CT) CBF studies with intravenous acetazolamide introduced 20 minutes prior to the second study. Patients were assigned to one of two vasoreactivity groups. Group 2 included individuals who experienced a CBF reduction of more than 5% in at least one vascular territory and had a baseline flow of 45 cc/100 gm/min or less. Group 1 included all other individuals. Any territory with volume loss on CT of more than 50% was eliminated from analysis. Sixty-eight individuals were followed at 6-month intervals for a mean of 24 months. In Group 1 two strokes were observed contralateral to the side with lowest reserve, for a stroke incidence of 4.4%; in Group 2 eight strokes were observed ipsilateral to the side with lowest reserve, for a stroke incidence of 36%. The latter group had a 12.6 times greater chance of stroke (p = 0.0007). History of stroke, history of transient ischemic attacks, baseline CBF, and degree of stenosis were not associated with an increased stroke rate. In this study, significantly compromised vascular reserves accompanied by relatively low initial flow identified individuals who subsequently demonstrated a significantly increased rate of ipsilateral stroke.

Acetazolamide↗
PubMed1993

Athletic mouth guards--one town's approach.

A program to produce inexpensive, custom mouth guards for high school basketball players was implemented by teams of dentists who took impressions, fabricated and then delivered the mouth guards. This community service involved three hours of donated time; the player or school was charged $7.50 for materials per mouth guard. The potential reduction of dental related injuries is immeasurable, and it is hoped that other cities will adopt a similar program.

Adolescent↗
PubMed1993

A prototype multidisciplinary cancer screening clinic for the military medical facility.

Optimal treatment of cancer depends upon early diagnosis. With an aging retiree and dependent population, cancer diagnosis and management must be addressed by military medical treatment facilities (MTFs) in a coherent and cost-effective fashion. A prototype multidisciplinary cancer screening clinic is described which interdigitated MTF and local American Cancer Society resources. Sites screened included breast, prostate, skin, cervix, and oral cavity, with mammograms, prostate-specific antigens, PAP smears, and physical exams, as appropriate. Of 194 patient contacts over a 4-hour period, eight cancers were found and subsequently treated (five skin, three prostate). Patient selection criteria, screening results by site, lessons learned, and recommendations for future clinics are discussed. The multidisciplinary screening clinic is readily applicable to the MTF setting, cost-effective, and provides an invaluable service to eligible patients.

Ambulatory Care Facilities↗
PubMed1992

Massive epithelium-lined inclusion cysts after scleral buckling.

Two patients with massive epithelium-lined inclusion cysts of the orbit became symptomatic five and 16 years after scleral buckling. Each patient described diplopia and displacement of the previously treated eye. An orbitotomy in the first patient disclosed a loculated epithelium-lined inclusion cyst that extended posteriorly from the insertion of the inferior rectus muscle nearly to the apex of the orbit. In the second patient, a loculated epithelium-lined inclusion cyst extended into the superior nasal portion of the orbit from its origin near the insertions of the superior and medial recti muscles. We speculated that epithelial cells of the conjunctiva were shed at the time of scleral buckling and became lodged in the exposed sulcus created by the surgical retraction of Tenon's capsule. Here they proliferated and formed the large epithelium-lined cysts. In each patient, removal of the cyst was followed by a decrease in diplopia as the displaced globe returned toward its normal position.

Aged↗
PubMed1992

Novel molecular species of sphingomyelin containing 2-hydroxylated polyenoic very-long-chain fatty acids in mammalian testes and spermatozoa.

Polyenoic very-long-chain fatty acids (VLCFA) have been shown to be localized in unusual molecular species of sphingomyelin in the testes and spermatozoa of the ram, bull, rat, and boar and in the spermatozoa of man. The composition of polyenoic VLCFA-sphingomyelin was comparable in the testes and spermatozoa of each mammalian species; however, the sphingolipid was more concentrated in spermatozoa. The composition of testicular and spermatozoan polyenoic VLCFA-sphingomyelin differed considerably between animal types. Human spermatozoa mainly contained n-6 polyenoic VLCFA with two to four double bonds and even-carbon chain lengths up to 32. In ram and bull testes and spermatozoa, n-3 and n-6, tetra-, penta-, and hexaenoic VLCFA with even-carbon chain lengths up to 34 predominated. In rat and boar testes and spermatozoa, the polyenoic VLCFA were mainly n-6 derivatives with three to five double bonds and even- and odd-carbon chain lengths up to 34. The testes and spermatozoa of the latter two animal species contained 2-hydroxylated, in addition to non-hydroxylated, polyenoic VLCFA in sphingomyelin. This is the first time that 2-hydroxylated polyenoic VLCFA have been recognized in biological systems. Non-hydroxylated polyenoic VLCFA were initially observed in the sphingomyelin of rat testes 25 days after birth, followed by 2-hydroxylated derivatives at 30 days. The total amount of polyenoic VLCFA associated with rat testicular sphingomyelin increased dramatically from 25 to 40 days of postnatal life and then remained constant to 60 days (sexual maturity). The ratio of 2-hydroxylated to non-hydroxylated polyenoic VLCFA increased during this period. Polyenoic VLCFA-sphingomyelin seems to occur exclusively in the testes and spermatozoa of mammals, and it is postulated that this lipid plays a role in reproduction.

Animals↗
PubMed1992

Very long-chain fatty acids in peroxisomal disease.

Fatty acids with from 24 to 28 carbon atoms (very long-chain fatty acids, VLCFA) are present in small amounts in all mammalian tissues. Even longer chain fatty acids with from 30 to 38 carbon atoms (ultra-long-chain fatty acids, ULCFA) are found in certain specialized tissues including retina, brain, and spermatozoa. In patients with inherited defects in peroxisomal structure and/or function, there is an accumulation of VLCFA in most tissues, while VLCFA and ULCFA levels are increased in brain. The most pronounced changes occur in those patients who have defects in peroxisomal assembly (Zellweger syndrome, infantile Refsum's disease, and neonatal adrenoleukodystrophy). In the brain of these individuals, ULCFA are distributed largely in molecular species of phosphatidylcholine with penta-, hexa-, and heptaenoic acids. In contrast, patients with X-linked adrenoleukodystrophy have increased levels of phosphatidylcholine with monoenoic rather than polyenoic ULCFA. A defect in a peroxisomal VLCFA CoA synthetase or ligase has been reported for these patients, but assembly of their peroxisomes is apparently normal. We speculate that ULCFA are normal products of carbon chain elongation. We have confirmed this by demonstrating the elongation of [1-14C]hexacosatetraenoic acid (26:4n-6) by rat brain in vivo to a series of longer chain tetraenoic acids with carbon chain lengths up to 34. Elongation to ULCFA can occur as well in non-neural tissues as shown by detection of labeled saturated and monoenoic fatty acids with up to 32 carbon atoms after incubation of normal and Zellweger syndrome fibroblasts with [2-14C] acetate. Increased labeling of VLCFA and ULCFA is observed in cells from patients with peroxisomal disorders. Our data suggest that ULCFA with up to at least 32 carbon atoms are formed normally, as a part of the elongation process in most mammalian tissues, and that control of carbon chain elongation is a major function of peroxisomes. Impairment of this function as occurs in peroxisomal disease results in the accumulation of VLCFA and ULCFA. The relative enrichment in normal tissues of ULCFA such as 32:6n-3 in ram and bull spermatozoa and 36:4n-6 in human and rat brain suggests a probable physiological role for this class of fatty acids in these tissues.

Adolescent↗
PubMed1992

Monoenoic fatty acids in human brain lipids: isomer identification and distribution.

The carbon chain length distribution and the double bond positional isomer composition of the monoenoic fatty acids of the lipids of total human brain tissue have been determined using gas chromatography and gas chromatography/mass spectrometry of the fatty acid methyl and picolinyl esters. The even chain length monoenoic C16 to C28 fatty acids contain predominantly two positional isomer series, the n-7 and n-9 cis homologues, whose relative proportion varies significantly with chain length. The odd chain length long-chain fatty acids consist of n-8 and n-10 isomers, whereas the odd chain length very long-chain (more than 22 carbon) fatty acids are n-7 and n-9 isomers.

Adolescent↗
PubMed1992

The Anticarsia gemmatalis nuclear polyhedrosis virus polyhedrin gene region: sequence analysis, gene product and structural comparisons.

The genomic region of the Anticarsia gemmatalis multiple nucleocapsid nuclear polyhedrosis virus (AgMNPV) strain 2D encoding the polyhedrin gene was cloned and mapped, and a 2085 bp SphI-PstI fragment containing the gene was sequenced. The polyhedrin polypeptide of the parental isolate AgMNPV was manually sequenced, and the amino acid sequence obtained agreed with that deduced from the DNA coding region sequence. AgMNPV and Orgyia pseudotsugata MNPV (OpMNPV) are similar in terms of promoter structure and polyhedrin primary sequence, and the polyhedrin gene of both viruses is transcribed in the anti-clockwise direction in relation to their physical maps. The region upstream from the polyhedrin gene of AgMNPV, OpMNPV, Bombyx mori NPV and Autographa californica MNPV (AcMNPV) was compared and this showed that the open reading frame (ORF) common to all four viruses (ORF 5) has sequence homology with the AcMNPV 25K gene. The sequences between ORF 5 and the polyhedrin gene were found to be variable among the polyhedrin gene loci compared. Additionally, conserved elements in the promoters of the very late genes encoding polyhedrin and granulin, and those encoding two p10 proteins were found to share sequence homology and positional similarity with consensus regions in the conserved boxes A and C, responsible for binding transcription factors to eukaryotic 5S ribosomal RNA genes, and to box C of tRNA genes.

Amino Acid Sequence↗
PubMed1992

Hypertension with hemodilution prevents multifocal cerebral hypoperfusion after cardiac arrest in dogs.

BACKGROUND: Improved neurological outcome with postarrest hypertensive hemodilution in an earlier study could be the result of more homogeneous cerebral perfusion and improved O2 delivery. We explored global, regional, and local cerebral blood flow by stable xenon-enhanced computed tomography and global cerebral metabolism in our dog cardiac arrest model. METHODS: Ventricular fibrillation cardiac arrest of 12.5 minutes was reversed by brief cardiopulmonary bypass, followed by life support to 4 hours postarrest. We compared control group I (n = 5; mean arterial blood pressure, 100 mm Hg; hematocrit, greater than or equal to 35%) with immediately postarrest reflow-promoted group II (n = 5; mean arterial blood pressure, 140-110 mm Hg; hypervolemic hemodilution with plasma substitute to hematocrit, 20-25%). RESULTS: After initial hyperemia in both groups, during the "delayed hypoperfusion phase" at 1-4 hours postarrest, global cerebral blood flow was 51-60% of baseline in group I versus 85-100% of baseline in group II (p less than 0.01). Percentages of brain tissue voxels with no flow, trickle flow, or low flow were lower (p less than 0.01) and mean regional cerebral blood flow values were higher in group II (p less than 0.01). Global cerebral oxygen uptake recovered to near baseline values at 3-4 hours postarrest in both groups. Postarrest arterial O2 content, however, in hemodiluted group II was 40-50% of that in group I. Thus, the O2 uptake/delivery ratio was increased (worsened) in both groups at 2-4 hours postarrest. CONCLUSIONS: After prolonged cardiac arrest, immediately induced moderate hypertensive hemodilution to hematocrit 20-25% can normalize cerebral blood flow patterns (improve homogeneity of cerebral perfusion), but does not improve cerebral O2 delivery, since the flow benefit is offset by decreased arterial O2 content. Individualized titration of hematocrit or hemodilution with acellular O2 carrying blood substitute (stroma-free hemoglobin or fluorocarbon solution) would be required to improve O2 uptake/delivery ratio.

Animals↗
PubMed1992

The use of vaccines in renal failure.

Renal insufficiency is characterised by impaired host defences, which are compromised further by each of the 3 modes of renal replacement--haemodialysis, continuous ambulatory peritoneal dialysis (CAPD) and renal transplantation. Reduced renal clearance of unknown toxins, possible development of nutritional deficiencies and administration of immunosuppressive medications lead to aberrant immune regulation early in the course of renal failure. This results subsequently in increased frequency and severity of infection. Vaccination plays an important role in attenuating this infection risk, but impaired cell-mediated and humoral immunity contraindicates the use of live vaccines and engenders suboptimal and short-lived antibody responses to inactivated vaccines. Reinforced vaccination schedules, increased vaccine dosage and concomitantly administered adjuvant immunomodulators have variably improved the defective antibody responses to certain vaccines. Immunisation against hepatitis B virus has resulted in a significant decrease in prevalence and incidence of this infection in haemodialysis units. Similarly, the inoculation of influenza vaccine in patients with uraemia and of polyvalent pneumococcal vaccine in special risk circumstances has been recommended because of perceived reductions in morbidity and mortality from infection with these agents. Cytomegalovirus (CMV) vaccine may attenuate CMV disease severity in recipients of renal allografts. Staphylococcus aureus vaccine, on the other hand, is ineffective in preventing peritonitis or exit site infections in patients receiving CAPD. Other killed vaccines have not been comprehensively studied, but generally have the same indications for use as in normal individuals. However, the protection that these vaccines afford may be either inadequate or transient, so that other infection control strategies should be simultaneously implemented.

Bacterial Infections↗
PubMed1992

Effects of compensatory growth on some body component weights and on carcass and noncarcass composition of growing lambs.

A trial was conducted in 1983 and repeated in 1984 to measure effects of restricted feed intake and realimentation on weights of organs and on carcass and noncarcass composition. A total of one hundred six weaned lambs from two breeds (Timahdit and D'man) and a breed cross (Ile de France x D'man) were used in both years. Lambs were allotted to one of six feed intake regimens: HH (ad libitum access to feed from 21 to 30 kg); HM (ad libitum access to feed from 21 to 26 kg then 70% ad libitum to 30 kg); MH (70% ad libitum from 21 to 26 kg then ad libitum to 30 kg); MM (70% ad libitum from 21 to 30 kg); LH (restricted to lose weight from 21 to 17 kg then ad libitum to 30 kg); and LM (restricted to lose weight from 21 to 17 kg then 70% ad libitum to 30 kg). Weights of visceral organs and mesenteric and kidney fat showed dramatic responses to alteration of feed allowances. After recovery from 20% live weight loss, weight of liver equaled or exceeded that of both the ad libitum and 70% refed lambs. Mesenteric and kidney fat did not. Refeeding was accompanied by an increase in water (P less than .05) and a decrease in fat (P less than .01) of both carcass and noncarcass components. These results indicate that weight loss of lambs incurred during feed shortage was largely in internal organ weights, and that these lambs can recover these losses during realimentation and undergo compensatory growth with better feed efficiency and lean carcasses.

Adipose Tissue↗
PubMed1992

Effects of undernutrition and refeeding on weights of body parts and chemical components of growing Moroccan lambs.

Forty-four intact, male lambs (20 Timahdit and 24 D'man) were used to assess the effects of 22% (from approximately 25 to approximately 20 kg) and 31% (from approximately 25 to approximately 17 kg) live weight loss and the subsequent refeeding to initial BW on changes in body components. Body composition was determined using a serial slaughter technique at 17, 20, and 25 kg live weight during normal growth, weight loss, and refeeding phases. Reduction in live weight from 25 to 20 kg was associated with greater loss of visceral organs (30%) and internal fat (75%) than carcass loss (19%). Further body weight loss (from 20 to 17 kg) involved carcasses to a greater extent than internal organs. The composition of BW loss consisted of 53% water, 28% fat, and 15% protein. Refeeding was associated with a rapid increase in organ weights and less fat regeneration. Although total internal organs recovered only 90% of their original weight, liver and kidneys regained all their weight. At the same slaughter weight, carcass and noncarcass components of refed lambs were leaner because of lower fat content in these components.

Adipose Tissue↗
PubMed1992

The cost of quality assurance/quality control.

Good Manufacturing Practice Guidelines have an inherent philosophy to maintain high standards and to promote uniformity within trading areas. Reaching these standards in some countries and maintaining them in others is costly. The Cost of Quality is regarded as a significant indicator of business performance. Quality costs are increasing as demands for improved accuracy and precision are made on the industry. The paper also details actual costs for validating a modern biological production facility and establishing biological quality control facilities. Bench mark quality control testing costs for a typical large and small animal vaccine are given.

Animals↗
PubMed1992

Quick blots and nonradioactive detection of DNA probes for the identification of mosquitoes.

The quick blot protocol is an improved technique for preparing crude insect homogenates for hybridization to nucleic acid probes. Individual insects are ground in wells of a microtiter plate and transferred to a dot blot manifold. This allows preparation of multiple filters and provides uniformity and an orderly arrangement of samples. The high background detection resulting from use of crude insect homogenates with nonradioactive detection systems was eliminated by incubating quick blot filters in a laundry stain remover containing proteases. We used mosquito species-specific DNA probes to demonstrate the effectiveness of nonradioactive DNA labeling systems with quick blots.

Animals↗
PubMed1991

Infrared measurements of HF and HCl total column abundances above Kitt Peak, 1977-1990: seasonal cycles, long-term increases, and comparisons with model calculations.

Series of high-resolution (approximately 0.01 cm-1) solar absorption spectra recorded with the McMath Fourier transform spectrometer on Kitt Peak (altitude 2.09 km, 31.9 degrees N, 111.6 degrees W) have been analyzed to deduce total column amounts of HF on 93 different days and HCl on 35 different days between May 1977 and June 1990. The results are based on the analysis of the HF and H35Cl (1-0) vibration-rotation band R(1) lines which are located at 4038.9625 and 2925.8970 cm-1, respectively. All of the data were analyzed using a multilayer, nonlinear least squares spectral fitting procedure and a consistent set of spectroscopic line parameters. The results indicate a rapid increase in total HF and a more gradual increase in total HCl with both trends superimposed on short-term variability. In addition, the total columns of both gases undergo a seasonal cycle with an early spring maximum and an early fall minimum, with peak-to-peak amplitudes equal to 25% for HF and 13% for HCl. In the case of HF, the changes over the 13 years of measurement are sufficiently large to determine that a better fit is obtained assuming a linear rather than an exponential increase with time. For HCl, linear and exponential models fit the data equally well. Referenced to calendar year 1981.0 and assuming a sinusoidal seasonal cycle superimposed on a linear total column increase with time, HF and HCl increase rates of (10.9 +/- 1.1)% yr-1 and (5.1 +/- 0.7)% yr-1 and total columns of (3.17 +/- 0.11) x 10(14) and (1.92 +/- 0.06) x 10(15) molecules cm-2 (2 sigma) are derived, respectively; the corresponding best fit mean exponential increase rates are equal to (7.6 +/- 0.6)% yr-1 and (4.2 +/- 0.5)% yr-1 (2 sigma). Over the 13-year observing period, the HF and HCl total columns increased by factors of 3.2 and 1.8, respectively. Based on HF and HCl total columns deduced from measurements on the same day, the HF/HCl total columns ratio increased from 0.14 in May 1977 to 0.23 in June 1990. Short-term temporal variations in the HF and HCl total columns are highly correlated; these fluctuations are believed to be caused by dynamical variability in the lower stratosphere. The results of this investigation are compared with previously reported measurements and with time-dependent, two-dimensional model calculations of HF and HCl total columns based on emission histories and photo-oxidation rates for the source molecules.

Astronomical Phenomena↗
PubMed1991

Herpes simplex type 1 infections in group day care.

To characterize patterns of herpes simplex virus type 1 infection, illness and transmission among children in group day care, the data for 115 children who had been followed longitudinally from early infancy in a research day care center were examined. By 5 years of age 37% of study children had evidence of herpes simplex virus type 1 infection as demonstrated by virus isolation and/or seroconversion. The incidence of infection was highest among children 1 to 2 years old. Four small clusters of primary infections were observed over the 12-year study period but no cluster involved more than 6 children. Fifty-five percent of primary infections occurred during these small outbreaks; the remainder were sporadic. Gingivostomatitis was observed in 26% of children with primary culture-proved infections; no child with infection identified solely by serologic means had a history of gingivostomatitis. The occurrence of gingivostomatitis did not appear to be associated with increased transmission of herpes simplex virus type 1 infection in this day-care setting.

Antibodies, Viral↗