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Biomedical subjects

H Alexander

Publications and source records attributed to H Alexander.

At least 163 records · Page 9Linked to original sources
PubMed1984

Infections simulating bone tumors. A review of subacute osteomyelitis.

The problem of differentiating primary bone tumors from subacute osteomyelitis was reviewed in 15 typical cases. Presenting symptoms, duration of illness, admitting laboratory data, and location of the pathologic condition were of little assistance in diagnosis. Preoperative diagnoses included benign and malignant neoplasms as well as osteomyelitis. In all cases the final diagnosis of subacute osteomyelitis was made only after open biopsy. Surgical curettage combined with appropriate antibiotic therapy was deemed essential for adequate treatment of this infectious process. Drug therapy included three to six weeks of parenteral antibiotics followed by three to six weeks of oral antibiotics. The protocol for duration of antibiotic therapy was based on the type of bacteria, the antibiotic serum levels achievable via the oral route, and patient compliance.

Adolescent↗
PubMed1983

Chemically synthesized peptides of hepatitis B surface antigen duplicate the d/y specificities and induce subtype-specific antibodies in chimpanzees.

Synthetic peptides, predicted from the nucleotide sequence of the S gene of hepatitis B virus were analyzed in terms of the established specificities of the hepatitis B surface antigen. The analysis indicated that the group-specific alpha antigen is composed of at least three nonoverlapping sequences and that a relatively hydrophilic region of the surface antigen protein, spanning amino acid residues 110-137, specifies the major d and y subtype system. The d/y subtype appears to depend on changes in one or more variable amino acids at positions 127, 131, and 134 of the hepatitis B surface antigen protein. Peptide 49 (consisting of amino acid sequences of the y subtype for the region 110-137), coupled to a carrier protein and mixed with an adjuvant, stimulated a brisk anti-y response in chimpanzees, the relevant model of human response to hepatitis B virus immunization and infection. Experimental challenge with homologous hepatitis B virus resulted in a pattern of partial protection. The results offer promise for the application of chemically synthesized peptides as vaccines in the prophylaxis of hepatitis B virus disease.

Amino Acid Sequence↗
PubMed1983

Effect of mechanical load in wound healing.

This study was designed to investigate the effect of sequentially increasing mechanical load on healing incisions. Full-thickness incisions were made on the back of a young domestic pig. During the period of fibroplasia, one of the incisions was mechanically loaded with a subcutaneous tissue expander. Mechanical and histological evaluations of mechanically loaded and control incision areas indicated that the mechanical stress encouraged healing and remodeling of dermal tissue.

Animals↗
PubMed1983

Absorbable polymer-filamentous carbon composites--a new class of tissue scaffolding materials.

The utility of filamentous carbon in tendon and ligament repair is limited by its premature mechanical degradation. When filamentous carbon is coated with an absorbable polymer, polylactic acid (PLA), a composite material results which serves as a tissue scaffold, maintaining its integrity long enough for new tissue to grow in and around it before it gradually degrades. Biocompatibility studies showed excellent tissue response to the PLA-carbon composite. Dog patellar tendons and medial collateral ligaments and rabbit Achilles tendons fashioned from the composite were then implanted. The implants allowed almost immediate resumption of activity and encouraged the growth of new structures histologically and mechanically similar to the natural structures. Its high initial strength, rapid ingrowth and benign tissue reaction suggest that this new composite material may be useful in the treatment of tendon and ligament injuries in humans. Consequently, the material was entered into limited clinical trials. To date, thirty patients have had implant surgery for the repair of extensor mechanisms, knee ligaments, Achilles tendons, and rotator cuffs. At this writing, seven month follow-up is available. Early results are encouraging.

Absorption↗
PubMed1982

Immunogenic structure of the influenza virus hemagglutinin.

We chemically synthesized 20 peptides corresponding to 75% of the HA1 molecule of the influenza virus. Antibodies to the majority (18) of these peptides were capable of reacting with the hemagglutinin molecule. These 18 peptides are not confined to the known antigenic determinants of the hemagglutinin molecule, but rather are scattered throughout its three-dimensional structure. In contrast, antibody raised to intact hemagglutinin did not react with any of the 20 peptides. Taken together these results suggest that the immunogenicity of an intact protein molecule is not the sum of the immunogenicity of its pieces.

Amino Acid Sequence↗
PubMed1982

A phalangeal fracture model--quantitative analysis of rigidity and failure.

Nine types of internal fixation techniques were tested in 4-point bending using a pig metacarpal model for phalangeal fractures. Levels of bending rigidity and bending moments at failure were determined, and the modes of failure are described. Plate and screw fixation afforded the greatest rigidity, and epiphyseal fractures occurred, leaving intact the test section. Flexible wire loop fixation failed by wire cutting into bone when a square knot was used. Twisted wire unraveled when placed in tension. Depending on the fracture type and the wire placement. Kirschner wires failed either by slipping in the bone, twisting in the bone cortex, or bending at the bone cortex interface. Rigidity varied widely depending on the way in which the wires were employed.

Animals↗
PubMed1982

Yersinia enterocolitica in Kansas. Attempted recovery from 1,212 patients.

An attempt was made to isolate Yersinia enterocolitica, by cold enrichment, from the stool of 1,212 patients seen at the Wesley Medical Center in Wichita, Kansas. Y. enterocolitica was isolated from 5 (0.4%) of the patients. Shigella was isolated from 36 (3.0%) patients while either Salmonella or Campylobacter were each isolated from 15 (1.2%) patients. Two of our five Yersinia isolates were from patients admitted to the hospital with diarrhea. One was from a patient who developed transient diarrhea while in the hospital, and the other two were from patients without diarrhea. In our opinion, the data do not justify the routine examination of stool specimens for Y. enterocolitica.

Aged↗
PubMed1982

Physiological changes in hyperactive children following the ingestion of food additives.

This study attempted to determine if the ingestion of artificial food additives would produce detectable changes in autonomic and/or central nervous system activity in hyperactive children. A single-case experimental design was used which entailed the comparison of heart rate and electroencephalographic (EEG) measures for hyperactive and control children. The physiological measures were obtained prior to and following the ingestion of drinks containing food additives or placebos, which were administered in a double-blind, randomized, crossover procedure. The hyperactive children exhibited a greater degree of physiological activity following both the placebo and the drink containing food additives than did the control children. However, the magnitude of physiological changes in the hyperactive children were greater in response to ingestion of the additives than to placebo. These physiological findings are consistent with behavioural data indicating that some hyperactive children are adversely affected by food additives.

Alpha Rhythm↗
PubMed1982

Iron deficiency and anemia among Indian women in Fiji.

In June 1979, 245 Hindu and 240 Moslem women of childbearing age (14-45 yr) living in a semi-rural area north of Lautoka were tested for anemia and for iron-deficiency. Ninety-six (39%) of the 245 Hindu women and 77 (32%) of the 240 Moslem women were anemic according to World Health Organization criteria. Most of the cases of anemia were due to iron-deficiency. The prevalence of anemia did not change significantly with advancing age or increasing parity. Hookworm ova were found on examination of a single specimen of feces in 27 (14%) of 195 Hindu and 50 (24%) of 209 Moslem women. The presence of hookworm did not correlate with anemia. The red cell folate level was less than 160 micrograms/l in 117 (24%) of 478 women and the serum vitamin B12 level was less than 100 ng/l in 47 (10%) of 476 women. Subnormal levels of these vitamins did not correlate with anemia. The serum ferritin was determined to assess tissue iron stores. Two-hundred-and-twenty-four (46%) of 484 Indian women tested had serum ferritin values of less than 10 microgram/l; 400 (83%) had ferritin values of less than 26 microgram/l. The high prevalence of iron deficiency appears to be due predominantly to dietary factors.

Adolescent↗
PubMed1982

Herpes simplex virus: a cause for concern.

Herpes simplex virus (HSV) is one of several sexually transmitted agents receiving increased attention. HSV infection is a serious problem due to: the increasing number of cases; its ability to remain latent in the host and periodically cause recurrent infection; and lack of effective treatment. HSV may be acquired by infants delivered vaginally to a woman experiencing active infection. Neonatal herpes is a devastating disease, with 60% overall mortality and serious sequelae in many of the survivors. Infection by HSV is detected most reliably by virus culture, but cytology or direct antigen detection may also be useful especially when culture is not available.

Adolescent↗
PubMed1981

Chemically synthesized peptides predicted from the nucleotide sequence of the hepatitis B virus genome elicit antibodies reactive with the native envelope protein of Dane particles.

Thirteen peptides corresponding to amino acid sequences predicted from the nucleotide sequence of the hepatitis B surface antigen were synthesized chemically. The free or carrier-linked synthetic peptides were injected into rabbits, and 7 of the 13 elicited an antipeptide response. Antisera against four of the six soluble peptides longer than 10 amino acids were reactive with native antigen and specifically precipitated the 23,000- and 28,000-dalton forms from Dane particles. As the hepatitis molecule had not been chosen for study because of any structural feature suggesting unique opportunities for success, these results suggest that the strategy is general and should work for any protein as long as enough domains are studied. Peptides such as these could prove to be ideal vaccines.

Amino Acid Sequence↗