Biomedical subjects

J Culpepper

Publications and source records attributed to J Culpepper.

8 recordsLinked to original sources

PubMed1992

Molecular characterization of a Dirofilaria immitis cDNA encoding a highly immunoreactive antigen.

Dirofilaria immitis, a filarial nematode, is the causative agent of canine and feline heartworm disease. Previous research has demonstrated that immunity to D. immitis can be induced in dogs by repeated chemical abbreviation of infections while the parasite is a fourth-stage larva. Sera obtained from dogs immunized in this manner has been effective in passively transferring larval killing and stunting. These immune sera, by comparison to nonimmune sera from infected cohorts, recognize a number of unique D. immitis antigens, some of which are larval specific. In this study immune dog sera were used to screen a D. immitis larval cDNA expression library. Three overlapping cDNA clones, Di22, Di18 and Di16, were obtained that encode a portion of a large molecule, greater than 150 kDa, that is composed of multiples of a 399-bp repeat. This protein when immunoblotted with antibody against a recombinant expressed Di22 fusion protein is found in larval as well as adult extracts and excretory-secretory products, and is seen as a series of ascending subunits, each approximately 15 kDa larger than the previous one. This antigen is highly immunogenic, as evidenced by the strong reactivity of the recombinant expressed Di22 fusion protein with sera from immune dogs, microfilaremic dogs and infected amicrofilaremic dogs. While the function of this antigen is unknown it has significant sequence similarity with an allergen found in Ascaris.

Amino Acid Sequence↗

PubMed1991

Bright light effects on body temperature, alertness, EEG and behavior.

The immediate psychophysiological and behavioral effects of photic stimulation on humans [bright light (BL) of 5K lux or dim light (DL) of 50 lux] were assessed in male subjects (N = 43) under four different conditions. For one condition the same subjects (N = 16) received alternating 90-min blocks of BL and DL during the nighttime h (2300-0800 h) under sustained wakefulness conditions. A second condition was similar to the first except that subjects (N = 8) received photic stimulation during the daytime hours. For the third and fourth conditions different subjects received either continuous BL (N = 10) or continuous DL (N = 9) during the nighttime hours. For the nighttime alternating condition body temperature decreased under DL but either increased or maintained under BL. For the continuous light condition, body temperature dropped sharply across the night under DL but dropped only slightly under BL. Sleepiness was considerably greater under DL than under BL, and the difference became larger as the night progressed. Similarly, alertness, measured by EEG beta activity, was greater under BL, and nighttime performance on behavioral tasks was also generally better. There were no differential effects between BL and DL on any measure during the daytime. These data indicate that light exerts a powerful, immediate effect on physiology and behavior in addition to its powerful influence on circadian organization.

Adolescent↗

PubMed1990

Responsiveness to olfactory stimuli presented in sleep.

Whether humans react to olfactory stimuli presented in sleep was assessed. Responses of ten participants (mean age = 22.8 years) were recorded to repeated three-minute periods of either air alone or to a peppermint odor (0.26 mg/liter) during stage 2 sleep. These responses included behavioral (awakening, microswitch closure), autonomic (heart rate, EMG, respiration), and central (EEG) components. An odor delivery system is described comprised of an aquarium pump, Teflon and TYGON tubing, oxygen mask, filtering, and air flow valves. The data indicate that humans react behaviorally, autonomically and centrally to olfactory stimuli presented while sleeping. Although the percentage of overall responsivity to olfactory stimuli was low, significant differences (ANOVA) in responsivity to odor periods vs. nonodor periods were found for microswitch closures, EEG, EMG, and heart rate. For these measures eight or more of the ten participants showed this pattern of differential responsivity during odor and nonodor periods (Sign test = p less than 0.05). A time-of-night effect was also observed in that responsivity tended to be greatest early in the night. The effect on responsivity of other durations, concentrations, and odors requires additional research.

Adult↗

PubMed1988

Behavioral control of abnormal breathing in sleep.

Behavioral control of abnormal breathing in sleep was studied to determine if an intervention procedure could reduce apnea duration and also SaO2 (blood oxygen) desaturation levels. Sleep apnea patients (n = 11) were instructed while awake that tones would be presented in sleep whenever an apnea event occurred. They were told to breathe deeply to the tones and were given practice in doing so. Intervention and nonintervention hours alternated across 2 nights following 2 baseline nights. As expected, during the intervention hours, the duration but not the frequency of apneic events was reduced. The procedure also resulted in higher SaO2 levels during the intervention hours. Daytime sleepiness was not greater following intervention but sleep staging effects were observed. The results are sufficiently promising to warrant additional research.

Adult↗

PubMed1988

Schistosome heat-shock proteins are immunologically distinct host-like antigens.

Constitutively expressed schistosome homologues of heat-shock protein Hsp70 elicit a dominant antibody response in humans infected with either Schistosoma japonicum or Schistosoma mansoni; in each case the parasite antigens are immunologically distinct and noncrossreactive. The antigenic site of the homologues is located near their carboxyl terminus where phylogenetic divergence between Hsp70 proteins is greatest. Nucleotide sequence comparison between these regions predicts very few amino acid differences between the schistosome protein and that of their human host. Thus strikingly limited diversity is sufficient to elicit a discriminatory antibody response to these parasite host-like antigens.

Amino Acid Sequence↗

PubMed1987

A major immunogen in Schistosoma mansoni infections is homologous to the heat-shock protein Hsp70.

A 70,000 mol wt protein of Schistosoma mansoni was shown to be a major immunogen that invariably elicited an antibody response in infected humans. The universality of the response to this abundant antigen was confirmed in experimental animals and included the antibody response associated with the protective irradiated cercarial vaccine. We identified the 70,000 mol wt antigen as an S. mansoni homologue of the major eukaryotic heat-shock protein hsp70 by DNA sequence analysis of a cDNA insert from a lambda gt11 clone expressing the antigen and located the immunodominant epitope near the COOH-terminus of the molecule. The antigenic relationship of hsp70 to schistosome infections suggested an important role for this protein in parasite development and pathogenesis.

Amino Acid Sequence↗

PubMed1987

Control of masseter muscle tension during sleep.

This study evaluated whether muscle tension could be controlled during sleep. Twelve volunteers were assigned to an experimental condition or to a no treatment control group. Experimental subjects were instructed to reduce the tension in their masseter (jaw) muscle when signalled with an auditory tone. These subjects demonstrated cue-controlled tension reductions during awake training sessions. Although both groups evidenced muscle tension increases in response to the tones presented during sleep, experimental subjects produced significantly smaller increases in response to tone stimuli than did control subjects. More importantly, experimental subjects sustained lower tonic levels of muscle tension throughout the sleep sessions than did control subjects. Sleep was moderately disrupted for subjects in both groups. However, experimental subjects evidenced the greatest tension reductions during those responses in which they shifted to a lighter stage of sleep rather than fully awakening. These data suggest that muscle tension can be moderated during sleep.

Adolescent↗

PubMed1987

Schistosome elastases: biological importance, structure, function and stage-specific expression.

Larval schistosomes (Digenea: Trematoda) invade their definitive host by directly penetrating the skin. During the process they secrete a number of macromolecules, ostensibly to facilitate their entry. Among these we have identified and characterized a dominant proteolytic species: a serine protease capable of fragmenting keratin, types IV and VIII collagen, proteoglycan, fibronectin, laminin, and elastin. The enzyme exhibits the specificity characteristic of elastases, has a molecular mass of 30,000 Da and pI of 7.8, and is potently immunogenic in its native form. Specificity of the active site has been analysed, tetrapeptides having large hydrophobic or aromatic amino acids at size P1 serving as best substrates. The amino terminal 20 amino acids of the mature enzyme have been sequenced and the information derived has been used to construct an oligonucleotide (22-mer) complement of its corresponding mRNA. The latter has been used to establish, by Northern analysis, that expression of the enzyme is stage specific (differing in this respect from most schistosome immunogens), and under transcriptional control. Transcripts are encoded by a multigene family. Several cDNAs hybridizing to the oligonucleotide have been isolated, subcloned into bacteriophage M-13, and sequenced by the di-deoxy method. It is our expectation that this line of investigation will lead towards: (i) an anti-infection vaccine; (ii) a means for chemically preventing infection (using enzyme inhibitors), and/or (iii) a rapid diagnostic assay of prepatent infection.

Amino Acid Sequence↗