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Biomedical subjects

G Silber

Publications and source records attributed to G Silber.

8 recordsLinked to original sources
PubMed1990

Comparison of the in-vivo and in-vitro response to ragweed immunotherapy in children and adults with ragweed-induced rhinitis.

In order to compare results of allergen immunotherapy in paediatric and adult populations, 22 children with a history of ragweed hay fever were matched with an equal number of adults for skin sensitivity to ragweed and all were given a 1-year course of immunotherapy with a partially purified ragweed extract. Biological responses were measured by nasal challenges with ragweed before therapy was started, after 12 weekly injections and when the maintenance dose had been reached and also by methacholine bronchoprovocation tests before and after 12 months of therapy. Skin-test sensitivity to ragweed and control allergens, and ragweed-specific IgE and IgG antibody responses were measured at the same intervals as the challenges and at the end of the study. The effect of the therapy on clinical symptoms was not evaluated. Before therapy the groups of adults and children were comparable by all indices, except for TAME esterase activity in nasal washes during ragweed nasal challenge which was significantly lower in children. During treatment, mediators released during sequential nasal challenges declined to undetectable levels in most patients and changes in nasal ragweed sensitivity were comparable in both groups. Ragweed IgE increases after 12 weeks of therapy and IgG levels at maintenance therapy tended to be higher in the children, but neither difference was statistically significant. At the end of the study IgE and IgG antibody levels were comparable in both groups. Results of methacholine inhalation tests did not change significantly in either group. The decrease in skin sensitivity to ragweed was similar in both groups. We conclude that ragweed immunotherapy leads to immunological and biological consequences that are comparable in children and adults.

Adolescent↗
PubMed1990

Lower gastrointestinal bleeding.

The differential diagnosis of lower gastrointestinal bleeding in children can be reduced markedly simply by taking into account the age of the child. The clinical condition of the patient can further help narrow the diagnostic possibilities. Newborns and infants who are clinically unstable are more likely to have diseases such as necrotizing enterocolitis, volvulus, Hirschprung disease, intussusception, or Meckel diverticulum. A baby who appears healthy should be examined for swallowed blood, allergic colitis, anal fissures, or lymphonodular hyperplasia. An older child of healthy appearance with bleeding is likely to have a juvenile polyp or infectious colitis, but a child who appears sick may have hemolytic uremic syndrome, Henoch-Schoenlein purpura, or inflammatory bowel disease. This information, along with that gleaned from the physical examination, can lead the pediatrician to determine the need for specific tests, such as abdominal radiographs, stool cultures, and an endoscopic evaluation. We have come a long way in our ability to diagnose the causes of lower gastrointestinal bleeding. With the availability of newer radiographic and nuclear medicine modalities and the ability to visualize the colon endoscopically, the need for exploratory laparotomy for diagnosis is rarer. While surgery may still be the therapy of choice, new diagnostic modalities give the surgeon much more preoperative information.

Child↗
PubMed1989

Attenuation of allergen sensitivity early in the course of ragweed immunotherapy.

During the course of an open immunotherapy (IT) study of ragweed (RW)-allergic patients, nasal mediator release was studied by provocation testing. All subjects had a history of seasonal RW rhinitis, positive skin puncture test to RW, and RW-specific IgE by RAST. Nasal challenge was performed with serial dilutions of RW extract, before and after 12 weekly injections, providing a cumulative dose of 0.22 microgram of Amb a I. Serum IgE and IgG and basophil histamine release with RW were also measured. By 12 weeks of IT, when only 1% of the usual maintenance level dose had been administered, mean histamine release and TAME-esterase activity in nasal washes decreased significantly (p less than 0.05 and p less than 0.01). Prostaglandin D2 release did not change. Skin sensitivity decreased (p less than 0.05), whereas RW-specific IgE increased (p less than 0.05). No significant change in basophil histamine release was observed for RW or a control antigen. Only six of 40 subjects had an RW-specific IgG rise greater than 0.05 microgram/ml. Changes in nasal sensitivity did not correlate with the increases in IgE or IgG or with the change in skin test sensitivity. These present data indicate that there is a significant decline in nasal sensitivity to inhaled RW very early in the course of IT. There is, however, no indication of a relationship between the decreased nasal sensitivity and the production of RW-specific IgG antibodies.

Adolescent↗
PubMed1988

In vivo release of inflammatory mediators by hyperosmolar solutions.

Hyperosmolar environments induce histamine release from mast cells and basophils in vitro. To assess whether the same stimulus induces mediator release in vivo, 15 healthy human volunteers underwent nasal challenges with instilled solutions of differing osmolalities: lactated Ringer's solution (257 +/- 3 mOsm/kg), isosmolar mannitol (277 +/- 6 mOsm/kg), and hyperosmolar mannitol (869 +/- 8 mOsm/kg). The effect of these challenges on the volume, osmolality, and inflammatory mediator content of subsequent 5-ml isosmolar lavages was determined. The volumes of lavages returned after hyperosmolar challenges were significantly greater than those after isosmolar challenges (5.5 +/- 0.2 ml versus 4.2 +/- 0.1 ml; p less than 0.01) and these lavage solutions had higher osmolalities. Even when corrected for increased volumes, the lavages after hyperosmolar challenges contained significantly higher quantities of inflammatory mediators such as histamine (29.0 versus 10.1 ng; p less than 0.01), TAME-esterase activity (32.7 versus 11.1 cpm x 10(-3); p less than 0.01), and immunoreactive leukotrienes (9.9 versus 3.4 ng; p less than 0.01). The changes in mediators were dose dependent in that incremental increase in challenge osmolality were associated with incremental increases in histamine release. Therefore, when exposed to hyperosmolar stimuli in vivo, the nasal respiratory airway releases inflammatory mediators and fluid rapidly shifts into the airway lumen. It has been suggested that the mediator release observed on breathing cold and dry air is due to increased osmolality of airway secretions; the present data confirm that osmotic variations at the airway surface can provide an adequate stimulus for cell activation.

Adult↗
PubMed1984

Gonorrhea in a five year-old boy with hematuria.

A case of hematuria due to gonorrheal infection occurring in a 5 year-old child is described. Since venereal disease in a prepubertal child may reflect sexual abuse, all cases of prepubertal gonorrhea should be carefully investigated.

Child Abuse↗
PubMed1980

Recent progress in oligonucleotide synthesis.

It was found that some improvements in oligoribo- and oligo-2'-deoxyribonucleotide synthesis via the phosphotriester approach could be achieved using the p-nitrophenylethyl group for phosphate protection due to its stability in the condensation step and its clean removal of DBU and DBN respectively. Recent results will prove the synthetic advantages over known procedures.

Bridged Bicyclo Compounds↗