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Biomedical subjects

L Jacobs

Publications and source records attributed to L Jacobs.

At least 73 records · Page 4Linked to original sources
PubMed1994

Glycoprotein gE-negative pseudorabies virus has a reduced capability to infect second- and third-order neurons of the olfactory and trigeminal routes in the porcine central nervous system.

We investigated the spread of glycoprotein gE (gE)-negative pseudorabies virus (PRV) and its rescued 'wild-type' strain into and within the central nervous system (CNS) of 3- and 10-week-old pigs. This is the first study that demonstrates PRV invasion of the porcine CNS via the synaptically linked neurons of the olfactory and trigeminal routes and that demonstrates the role of gE in this invasion. After intranasal inoculation with high doses of virus, gE-negative PRV replicated less efficiently in peripheral tissues. The titres of the gE-negative virus in the oropharyngeal mucosa, olfactory epithelium, draining lymph nodes and trigeminal ganglion were approximately 100-fold lower in 3-week-old pigs and 10-fold lower in 10-week-old pigs than titres of the 'wild-type' virus. In contrast to the 'wild-type' virus, titres of the gE-negative virus were very low or undetectable in the olfactory bulb, brain stem and other tissues of the CNS. Viral antigen of rescued 'wild-type' PRV and of gE-negative PRV was detected immunohistochemically in the olfactory epithelium and in neurons of the trigeminal ganglion, and also in the olfactory and trigeminal axons leading towards the CNS. But, in contrast to 'wild-type' virus, no viral antigen of the gE-negative virus was detected in second- or third-order neurons in the olfactory bulb or in the brain stem. We conclude that gE-negative PRV can infect first-order neurons of the olfactory and trigeminal routes and is able to spread via their axons towards the CNS. Yet, gE-negative PRV has a greatly reduced capacity to infect second- or third-order neurons. Finally, we report lateral spread of 'wild-type' PRV in the trigeminal ganglion, i.e. nonsynaptic transport from neuron to neuron. Possible mechanisms that could explain the reduced levels of the gE-negative virus in the CNS are discussed.

Aging↗
PubMed1994

Epitope-specific antibody response against glycoprotein E of pseudorabies virus.

In this study we investigated the epitope-specific antibody response against glycoprotein E (gE) of pseudorabies virus. Epitope-specific antibody responses were investigated by enzyme-linked immunoperoxidase monolayer assays. In a vaccinated crossbred pig population, most pigs responded to antigenic domain E and to a lesser degree to antigenic domains C and D. Only few pigs responded to antigenic domains F, A, and B. Using vaccinated pigs, we investigated the influence of two different pseudorabies virus strains and the genetic background of the host on the epitope-specific antibody response. More pigs infected with the virulent NIA-3 strain had a detectable antibody response against antigenic domains C, F and A than did pigs infected with the mildly virulent Sterksel strain (P < or = 0.05; Fisher's exact test). No differences in the epitope-specific antibody responses of two genetically different pig breeding lines were observed (P > or = 0.1; Fisher's exact test). In both breeding lines the incidence of the epitope-specific antibody response was comparable to that in the crossbred pig population. In addition, we studied the epitope-specific antibody responses were strikingly different and indicated that genetic background influenced the epitope-specific antibody response. Of the serum samples of mice with C57BL and a BALB background, 40 and 17% respectively, were positive in the one of the epitope-specific immunoassays. In contrast to pigs, mice responded predominantly to antigenic domain D and to a lesser degree to antigenic domains E and B. Only few mice had a detectable antibody response against antigenic domains C and A, and none had a detectable antibody response against antigenic domain F.

Animals↗
PubMed1994

Glycoprotein I of pseudorabies virus (Aujeszky's disease virus) determines virulence and facilitates penetration of the virus into the central nervous system of pigs.

In the present study we investigated the virulence and neural spread of pseudorabies virus (PRV) strains with mutations in the gene encoding glycoprotein I (gI) in 3-week-old pigs which were intranasally infected. Mutant M303 (lambda 125, 126) lacks amino acids valine-125 and cysteine-126 in an immunodominant antigenic region of gI which contains 2 discontinuous antigenic domains, whereas mutant virus M304 (lambda 59, 60) lacks amino acids glycine-59 and aspartic acid-60 in a continuous antigenic domain. Mutant M301 contains a frame shift mutation. Both mutants M301 (gI-) and M303 (lambda 125, 126) were not virulent for pigs, whereas mutant M304 (lambda 59, 60) was as virulent as wild-type PRV. All gI mutant viruses replicated in the oropharyngeal mucosa, although M304 (lambda 59, 60) and wild-type PRV replicated to higher titres than M303 (lambda 125, 126) and M301 (gI-). In contrast to M304 (lambda 59, 60) and wild-type PRV, both mutant viruses M301 (gI-) and M303 (lambda 125, 126) were not recovered from any part of the central nervous system at day 6 after infection. To study the spread of M301 (gI-) in the central nervous system in more detail, a second experiment was done in which 100-fold more virus was intranasally administered and virus was recovered from various tissues at day 4 after infection. Again, no gI-negative virus was isolated from the central nervous system. We concluded that deleting the amino acids valine-125 and cysteine-126 decreases virulence and reduces neurotropism to the same degree as deleting the gI protein. In addition, gI-negative virus does not spread in the central nervous system of pigs, probably because the transport of the virus across the synapse is hampered.

Animals↗
PubMed1993

Collagen fibrillogenesis in a three-dimensional fibroblast cell culture system.

The purpose of this study was to follow collagen fibril formation in a newly developed three dimensional cell culture system. Human neonatal foreskin fibroblasts were grown on a nylon mesh in Dulbecco's Modified Eagles Medium (DMEM) supplemented with 10% fetal calf serum and antibiotics. Fibrillogenesis was initiated by the addition of 50 micrograms/ml ascorbate to confluent cultures. Sample meshes were processed for electron microscopy or immuno-electron microscopy. Fibrils approximately 20-30 nm in diameter, with 67 nm periodicity, were first detected five days after the addition of ascorbate. As cultures progressed, cells organized into parallel layers between which collagen fibers continued to form and increase in diameter. By day 50, fiber diameter ranged from 30 to 80 nm and large bundles were seen. No collagen fibril formation occurred in control cultures to which no ascorbate was added. However, large amounts of microfibrils were observed. Antibodies against the aminopropeptide of type I procollagen were found to bind to fibrils with diameters less than 34 nm while antibodies against the aminopropeptide of type III collagen bound primarily to fibers which ranged from 35-54 nm in diameter. We believe that this system, which morphologically resembles a normal dermis, will serve as an excellent model for the study of collagen fibrillogenesis.

Cells, Cultured↗
PubMed1993

Circulating CD3+ CD4+ CD8+ T lymphocytes in multiple sclerosis.

Triple-antibody flow cytometry was used to search for distinctive populations of peripheral blood lymphocyte immunophenotypes in multiple sclerosis (MS). Using monoclonal antibodies to the cell surface markers CD3, CD4, and CD8, T cell subsets were quantified on a cohort of 31 MS patients (not treated with corticosteroids for at least 6 months), 30 healthy donors, and 14 patients with other autoimmune diseases (also corticosteroid treatment-free for at least 6 months). Untreated MS patients displayed a significantly greater population of CD3+CD4+CD8+ circulating T cells than healthy donors (P = 0.023). Patients with other autoimmune diseases displayed mean populations of CD3+CD4+CD8+ cells greater than normal donors and less than MS, but not significantly different from either. An additional 45 MS patients who had received corticosteroid therapy within the previous 6 months were phenotyped. Treatment of symptomatic MS with corticosteroids was associated with a smaller population of circulating CD3+CD4+CD8+ cells. Some MS patients have significantly greater numbers of peripheral blood T lymphocytes simultaneously expressing CD3, CD4, and CD8 surface markers than healthy donors and this population of cells may be reduced by corticosteroids treatment. This triple positive phenotype may be a manifestation of a systemic immune abnormality in MS.

Antigens, CD↗
PubMed1993

Deleting valine-125 and cysteine-126 in glycoprotein gI of pseudorabies virus strain NIA-3 decreases plaque size and reduces virulence in mice.

We investigated the function of antigenic domains on gI in virulence and immunogenicity. Three PRV gI mutants were constructed by deleting nucleotides coding for the following amino acids: valine-125 and cysteine-126, located in a discontinuous antigenic domain (M 303); glycine-59 and aspartic acid-60 located in a continuous antigenic domain (M304); and arginine-67 and alanine-68, located in a discontinuous antigenic domain (M305). Mismatch primers in the polymerase chain reaction were used to introduce the deletions. Anti-gI monoclonal antibodies were used in an immunoperoxidase monolayer assay to distinguish PRV gI mutants from wild-type PRV. The gI mutant viruses were tested for their growth in vitro and for their virulence in mice. The growth properties of PRV gI mutant virus M303 were comparable to the growth properties of a PRV gI-negative mutant (M301): both mutants produced small plaques in various cells, and when grown on swine kidney cells and chicken embryo fibroblasts, their growth was disadvantaged compared to wild-type PRV. However, in embryonal Balb/c mouse cells expressing gI, gI mutant viruses and wild-type PRV produced plaques of the same size, confirming that the mutations in gI are responsible for the small plaque phenotype. The growth properties of PRV gI mutant viruses M 304 and M 305 were comparable to the growth properties of wild-type PRV. When the mean time to death was used as the criterion, the gI mutant viruses M 301 and M 303 were significantly less virulent in mice than wild-type PRV. Four other, independently obtained, PRV mutants all carrying the valine-125 and cysteine-126 deletion (M 308, M 309, M 310 and M 311 respectively) exhibit the same phenotype. Our results show that deleting valine-125 and cysteine-126 in gI decreases plaque size and reduces virulence in mice to the same degree as deleting the gI protein.

Amino Acid Sequence↗
PubMed1993

Deleting two amino acids in glycoprotein gI of pseudorabies virus decreases virulence and neurotropism for pigs, but does not affect immunogenicity.

The virulence, pathogenicity and immunogenicity of two pseudorabies virus (PRV) variants were investigated in 3-week-old pigs that had been intranasally infected. Variant M303 (delta 125,126) lacked amino acids valine (125) and cysteine(126) in an immunodominant antigenic region of glycoprotein I (gI) containing two discontinuous antigenic domains, whereas M304 (delta 59,60) lacked amino acids glycine(59) and aspartic acid(60) in a continuous antigenic domain. M303 (delta 125,126) was not virulent for pigs, but M304 (delta 59,60) was as virulent as wild-type PRV: all pigs died within 8 days of infection. Both gI mutant viruses replicated in the oropharyngeal mucosa, although M304 (delta 59,60) replicated to higher virus titres than M303 (delta 125,126), and virus was recovered from various tissues. However, in contrast to M304 (delta 59,60), M303 (delta 125,126) was not recovered from any central nervous system (CNS) tissues examined. Thus, the tendency of PRV to locate in the CNS was markedly reduced by deleting amino acids valine(125) and cysteine(126) of gI. Pigs immunized with M303 were completely protected against challenge infection; no clinical signs of disease were detected, no virus was shed, and no secondary antibody response was detected. Thus, deleting amino acids valine(125) and cysteine(126) in gI decreases virulence and neurotropism and does not affect immunogenicity.

Amino Acids↗
PubMed1993

Culturing keratinocytes and fibroblasts in a three-dimensional mesh results in epidermal differentiation and formation of a basal lamina-anchoring zone.

The purpose of this study was to characterize an in vitro co-culture model in which fibroblasts grown in a three-dimensional nylon mesh were recombined with human keratinocytes. The cultures were kept for 3 and 5 weeks and then processed for electron microscopy. Keratinocytes showed reconstruction of an epidermis consisting of a basal layer with hemidesmosomes, a stratified epithelium with tonofilaments and desmosomes, a granular layer with keratinosomes and keratohyaline granules, and a transitional stratum corneum. Anchoring filaments, lamina densa, anchoring fibrils, bundles of elastin-associated microfibrils (diameters 10 nm) and fine collagen fibrils were formed. Collagen fibrils near the epidermis were much thinner than those in the lower levels. The present study shows that the dermal model containing metabolically active fibroblasts in their natural environment will support epidermal morphogenesis and differentiation including the formation of a basal lamina and anchoring zone.

Basement Membrane↗
PubMed1992

A population-based study of motorcycle injury and costs.

STUDY OBJECTIVE: To provide a population-based injury and cost profile for motorcycle injury in Connecticut. DESIGN: Population-based retrospective epidemiologic review of Connecticut death certificates, hospital discharge data, and police accident reports. RESULTS: Connecticut death certificates identified 112 deaths from motorcycle injuries for an annual death rate of 1.2 per 100,000 persons. Death rates were highest among 20- to 24-year-old men. Nonhelmeted motorcyclists were 3.4-fold more likely to die than were helmeted riders (P less than .05). An estimated 2,361 motorcycle-related hospital discharges resulted in an annual hospitalization rate of 24.7 per 100,000 persons. Head, neck, and spinal injuries accounted for 22% of all injuries. Total costs exceeded $29 million; 29% of hospitalized patients were uninsured, and 42% of the cost was not reimbursed to the hospitals. CONCLUSION: Motorcycle injuries contribute significantly to Connecticut's mortality, morbidity, and medical costs. Our study suggests that a uniform helmet law would save an estimated ten lives and prevent more than 90 nonfatal injuries in Connecticut each year at a cost savings to the state of $5.1 million. These data are crucial in advocating re-enactment of motorcycle helmet laws.

Abbreviated Injury Scale↗
PubMed1992

Immunochemical analysis of human kidney reticulin.

This study characterized the nature of reticulin fibrils from human kidney cortex by immunochemical analysis. Controls consisted of type I collagen fibrils derived from the kidney parietal capsule. Most of the fibrils in the capsule ranged in diameter from 60 to 80 nm whereas reticulin fibrils from the cortex ranged from 30-45 nm. Immunochemistry by light and electron microscopic examinations was carried out with antibodies directed against type I and type III collagens, their corresponding aminopropeptides, and decorin (PG-II). The ratio of type I to type III collagen was determined by cyanogen bromide peptide digests. This study showed that reticulin fibrils are hybrids of type I and type III collagens. Double immunoelectron microscopic examination showed that fibrils 20-25 nm consisted mainly of type I collagen some of which retained their aminopropeptide. Larger fibrils 30-35 nm labeled simultaneously for type I and type III collagens. However, most fibrils with diameters between 40-55 nm labeled for type III collagen and its corresponding aminopropeptide. No decorin was detected at the surface of reticulin fibrils. Purified reticulin consisted of 82% type III and 18% type I collagen whereas collagen derived from the capsule revealed 76% type I and 24% type III. The presence of the aminopropeptide of type III procollagen in reticulin fibrils is a striking feature and may play a role in regulating their diameter.

Collagen↗
PubMed1991

Is the ESR dead?

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Blood Sedimentation↗
PubMed1991

Selective paralysis of voluntary but not limbically influenced automatic respiration.

We describe a patient in whom a discrete infarction of the ventral basis pontis caused a complete loss of voluntary respiration, while automatic respiration remained intact. Respiratory excursions, quantified title volumes, and ventilatory response to carbon dioxide were normal, but the patient could not volitionally modify any respiratory parameters. Emotional stimuli producing laughter, crying, or anxiety appropriately modulated automatic respiration. This case established that pathways subserving limbic modulation of automatic respiration descend in the pontine tegmentum and/or lateral portion of the basis pontis spared by this lesion. Furthermore, descending limbic influences on automatic respiration are anatomically and functionally independent of the voluntary respiratory system.

Adult↗
PubMed1991

Decorin interacts with fibrillar collagen of embryonic and adult human skin.

Biglycan (PG-I, BGN) and decorin (PG-II, DCN) are small proteoglycans that have been isolated in cartilage, skin, and bone. Although the function of biglycan is unknown, there is biochemical evidence that decorin interacts with fibrillar collagens (type I, type II). The purpose of this study was to perform immunofluorescence and immunoelectron microscopy and immunoblotting of human embryonic and adult skin with antibodies directed against biglycan and decorin. These antibodies were developed against synthetic peptides of the core proteins of biglycan (amino acid sequence 11-24) and decorin (amino acid sequence 5-17). Immunofluorescence microscopy showed that decorin stained embryonic and adult collagen fibrils. Biglycan did not stain collagen, but it appeared to stain the pericellular matrix of embryonic mesenchymal cells. Immunoelectron microscopy revealed labeling of all collagen fibrils with decorin antibodies regardless of their diameter, often at 60-nm periodicity. Positive stains suggest that most of the labeling was in the gap of the D-period (d and e bands) and also in one of the steps (c band). Decorin was identified by immunoblotting in fetal and adult skin. Also, significant amounts of core protein was identified lacking the dermatan sulfate chain. This study suggests that the core protein of decorin interacts with collagen fibrils although its specific function remains unknown.

Adult↗
PubMed1991

Elastin-associated microfibrils (10 nm) in a three-dimensional fibroblast culture.

The purpose of this study is to present a three-dimensional dermal fibroblast model. Skin fibroblasts cultured in this system deposit large amounts of collagen and microfibrils. Fibroblasts were seeded onto a nylon filtration mesh and incubated in the presence or absence of ascorbic acid. Collagen fibril formation was found in the presence of ascorbic acid whereas microfibril formation was seen independent of ascorbic acid supplementation. Immunoelectron microscopy revealed that microfibrils were labeled with fibrillin at 67 nm periodicity. Isolated microfibrils studied by rotary shadowing had a beaded appearance consisting of beads linked to each other by a filamentous structure. The spaces between the beads ranged from 10.00-33.33 nm, suggesting that these microfibrils may have an extension-contraction mechanism. Furthermore, the size and spacing of the beads were similar to that seen in microfibrils from tissues (measured after rotary shadowing). Fibroblasts cultured in a three-dimensional mesh represent an effective in vitro model with which to study microfibril formation.

Cells, Cultured↗
PubMed1991

Quantitative evaluation of the penile vascular status by means of the 99mTc-penogram in conjunction with either papaverine or prostaglandin E1 in the anaesthetised baboon model.

The evaluation of both the arterial blood supply and the venous drainage of the penis is essential in the assessment of the impotent male. The vasoactive drugs papaverine and prostaglandin E1, as intracavernous injections, cause penile erections by influencing arterial blood supply and venous drainage. These drugs were used in a baboon model together with a 99mTc-penogram to provide information on the vascular status of the penis. An increase in penile blood pool was observed, more dramatic and rapid after administration of papaverine. A quantitative assessment of the vascular status seems possible and will next be monitored in a vascular-compromised baboon for purposes of clinical application.

Alprostadil↗
PubMed1991

Bronchial hyperresponsiveness in normal subjects during attenuated influenza virus infection.

Fourteen healthy male subjects with hemagglutination-inhibition antibody titers of 1:8 or less to homologous influenza A virus were studied. Six subjects received live, attenuated influenza virus by nasal drops and by aerosol. Although infection occurred in these six subjects, with the development of 4-fold or greater increases in hemagglutination-inhibition antibody titers, they remained asymptomatic. Eight subjects received placebo via the same route, and did not develop symptoms and showed no increase in antibody titer. Prior to administration of virus or placebo, histamine diphosphate aerosol increased airway resistance only slightly, and there was no difference between the virus and placebo groups. Two days after inoculation, bronchomotor responses in the placebo group were unchanged (p greater than 0.05), but in the virus-infected group, bronchomotor responses were significantly greater than in the preinfected state (p less than 0.01). Isoproterenol hydrochloride reversed and prevented the increase in airway resistance after histamine, suggesting that the bronchoconstriction was caused by smooth muscle contraction. Our findings indicate that transient, asymptomatic respiratory virus infection augments airway smooth muscle responses.

Adult↗