Search PubMed⌕ Search

Biomedical subjects

J Bacon

Publications and source records attributed to J Bacon.

At least 37 records · Page 2Linked to original sources
PubMed1989

Human pepsinogen C (progastricsin) polymorphism: evidence for a single locus located at 6p21.1-pter.

A series of six clones containing the entire human pepsinogen C gene (PGC) was identified in a cosmid vector library by using cDNA and oligonucleotide probes. The 10.7-kb PGC gene includes nine exons and exhibits a high degree of sequence identity (60%) with the functionally related pepsinogen A genes. The predicted amino acid sequence was identical with the partial amino-terminal and carboxyl-terminal sequences of purified pepsinogen C. An informative restriction fragment length polymorphism was detected with several restriction enzymes and involved an insertion or deletion of 100 bp of intron sequence located between exons 7 and 8. Evidence that there is only a single PGC gene in humans is presented. The PGC gene and the prolactin gene were regionally localized to 6p21.1-pter by analysis of mouse X human somatic cell hybrids.

Amino Acid Sequence↗
PubMed1989

Further characterization of a bacteriophage recovered from an avian strain of Chlamydia psittaci.

The genome of a 22 nm icosahedral phage which infects some avian Chlamydia psittaci strains recovered from domestic ducks has been characterized as a ss circular DNA molecule of about 4850 bases. The replicative form of this genome was isolated from purified chlamydial organisms. A restriction endonuclease cleavage site map of the genome was constructed from dsDNA synthesized in vitro from ss phage DNA and EcoRI fragments were then cloned into pUC9. The phage genome was detected only by Southern blot hybridization in C. psittaci which was productively infected with phage; no evidence was found for the integration of phage DNA into the chlamydial chromosome. Three viral polypeptides, of approximate Mr values 75K, 30K and 16.5K were identified when phage was analysed by SDS-PAGE. This virus, which we have designated Chp 1, is either an aberrant member of the Microviridae or the first member of a new bacteriophage family.

Animals↗
PubMed1989

A family exhibiting the cis-AB genotype.

Studies on blood samples from a 30-year-old woman of Korean origin, her husband and children, showed the presence of the cis-AB genotype in the mother and one child. The cis-AB red cells showed abnormal reactions with both polyclonal and monoclonal anti-B reagents and an elevated level of H antigen. The serum contained weak anti-B that reacted with normal B antigen but not with that on cis-AB cells. Normal levels of A substance but reduced levels of B and H substances were present in the saliva. Conversely, the serum showed reduced A and normal B and H blood group transferase activity.

ABO Blood-Group System↗
PubMed1986

Developmental differences in part/whole identification.

At issue in the present research was whether or not preschoolers are able to simultaneously perceive multiple aspects of an object. This issue was examined in 2 experiments in which 3-5-year-olds were asked to describe part/whole pictures (e.g., a "house made of crayons"). Prior developmental research has suggested that preschoolers typically fail to name both part and whole aspects of such pictures. In the present study, parts and wholes ranged from relatively "simple" to relatively "difficult" for preschoolers to identify and label. The results showed that even 3-year-olds frequently named both part and whole aspects of our "simple" pictures but were significantly less likely to name both aspects of more "difficult" pictures. Overall, the results suggest that multiple-aspect perception is available as early as 3 years of age, and that preschoolers' failure in previous studies to explicitly identify both part and whole aspects of the same object may reflect failure in verbal or metacognitive skills rather than in children's ability to perceive multiple aspects of an object.

Child Development↗
PubMed1982

Configurational differences in stereovision.

Retinal disparities which produce perceived depth in stereoscopic vision result from configurational differences in the retinal images in the two eyes of objective three-dimensional arrangements. Experiments reported earlier demonstrated special effectiveness of differences in the alignment in the vertical dimensions of the images of points that are at different depth. Here a stereoscopic experiment is reported where alignment differences were increased without altering disparity. An increase in perceived depth resulted and was measured by estimation and by matching. The reason for the special effectiveness of binocular alignment differences is discussed.

Depth Perception↗
PubMed1981

Interommatidial sensilla of the praying mantis: their central neural projections and role in head-cleaning behavior.

The compound eye of the praying mantis is covered with approximately 600 bristles and campaniform sensilla. Their afferents project to the brain, and to the suboesophageal and prothoracic ganglia. Cutting the eye branch of the dorsal tegumentary nerve (DTN), the peripheral nerve innervating the corneal sensilla, makes it impossible to initiate head grooming by tactile stimulation of the eye. This stimulus is a strong releaser of grooming behavior in normal animals. Head grooming can be initiated, after cutting the eye branch of the DTN, by stimulation of the frons (the operation leaves the sensory innervation of this part of the cuticle intact). Frame-by-frame analysis of films of head grooming after cutting the nerve reveals a reduction of the speed at which the forelimb is brushed across the surface of the head and eye. The significance of this finding is discussed in terms of a putative feedback loop from the corneal sensilla to the motor neurons controlling the grooming movements.

Animals↗
PubMed1981

Controlled studies of intranasal immunotherapy for ragweed pollenosis.

During 1978 a double blind study compared the efficacy of preseasonal short ragweed (RW) extract intranasal immunotherapy with a histamine placebo; in 1979 more prolonged treatment with a larger dose of polymerized ragweed (PRW) was evaluated. In neither year did the placebo-treated patients show significantly more severe disease as assessed by daily symptom diaries, examination in season, comparison of overall symptom severity with previous years or changes in nasal challenge tests. Following treatment in 1979 there was a significantly greater amount of secretory IgA and IgG ragweed antibodies secreted by the nose of the PRW-treated group, but these titers did not correlate with clinical results.

Administration, Intranasal↗
PubMed1980

Sexual dimorphism of motorneurons: timbal muscle innervation in male periodical cicadas and homologous structures in females.

In 17-year cicadas, only the male has a sound-producing apparatus. It consists of paired abdominal timbals, each driven by a specialized timbal muscle. Each muscle is innervated by a large timbal motorneuron. Having the largest axon in the auditory nerve, its central structure is readily elucidated with cobalt. The largest cell in the female auditory nerve is found to be a motorneuron that bears striking resemblance to the timbal motorneuron of the male. On the basis of their anatomy within the CNS, we consider these cells to be homologous, despite the fact that the female has no apparent timbal muscle. Cobalt-filling to the periphery reveals the target muscle of the female motorneuron to be one of the three tensor tympani muscles supporting the tympanum; these muscles are not found in the male. The evolutionary significance of these findings is discussed in terms of a possible loss of the sound-producing apparatus in females.

Animals↗
PubMed1977

The detection of line segments.

Many simple cells of the visual cortex have long narrow receptive fields, which are strongly excited by lines oriented along their long axis. In the present psychophysical analysis, we assume that there are similar independent 'subunits' which contribute, by probability summation, to the detection of a line. If a line segment is shorter than the subunit length, then extending the line length will increase the sensitivity of all the subunits affected by the line, and a relatively large increase in visual sensitivity will occur, corresponding to this 'physiological summation' within subunits. However, for a line segment which is much longer than the subunit length, the main effect of extending line length is to stimulate more subunits, resulting in a relatively small increase in sensitivity owing to probability summation. Thus a study of sensitivity (reciprocal threshold) as a function of line length may be used to test the subunit model and to estimate the subunit length. Here we use a quantitative model to demonstrate that sensitivity/line length data may be well fitted, assuming independent subunits having a constant length of 8-6'--in good agreement with the length of Adrews' "ff" units.

Adult↗
PubMedDate not supplied

Central venous alimentation: a prospective study of the frequency of metabolic abnormalities among medical and surgical patients.

Many studies have described the frequency of septic and technical complications of central venous alimentation (CVA), but metabolic complications of CVA have received scant attention. Among 100 consecutive medical and surgical patients receiving CVA under routine hospital conditions, at least one severe biochemical defect (above the 99th percentile ranking) was observed in 63 cases (63%). Uncontrolled hyperglycemia (defined as blood glucose greater than 300 milligrams per deciliter after more than 48 hours of CVA) was present in 47 individuals. Hypophosphatemia (serum phosphorus less than 2.0 milligrams per deciliter) occurred in 30 and was life-threatening (less than 1.0 milligrams per deciliter) in 6. Although liver function tests (LFT) remained stable or improved in 26% of the 34 evaluable subjects, 74% showed deterioration in one or more tests, and 35% showed deterioration in two or more tests. Deterioration was defined as an abnormal result that was 50% or more above baseline in patients having weekly LFT and CVA for a minimum of 10 days. The study involved 1378 patient-days of CVA, a mean of 14 days per patient with a range of 2 to 70 days, and an average of 2.2 catheter insertions per patient. Technical complications occurred in 3% and septic complications occurred in 4% of 220 catheter insertions. There was no significant difference in the type or frequencies of metabolic, septic, and technical complications occurring between medical and surgical patients. The findings suggest that many reports concerning septic and technical complications of CVA have promoted awareness of the problem and served to minimize these risks. However, this study demonstrates that serious metabolic complications of CVA occur at an unexpectedly high rate and that greater attention should be directed at their prevention.

Adolescent↗