Biomedical subjects

A Holm

Publications and source records attributed to A Holm.

At least 19 recordsLinked to original sources

PubMed1992

Synthesis and characterization of a 25-residue rubredoxin(II)-like metalloprotein and its valine-leucine mutant.

An iron-sulfur metalloprotein containing the 5-12 and 35-50 residues of Desulfovibrio gigas rubredoxin has been synthesized by Fmoc solid phase peptide synthesis and subsequent peptide folding. A Gly links the two residue chains between Val-5 and Glu-50. Sybyl Tripos structure optimization indicates only minor structural changes of the folded synthetic protein compared to the similar residue positions in the native protein. The UV-VIS spectrum of the reduced synthetic protein is very similar to that of native D. gigas rubredoxin and the molecular mass determined by laser mass spectrometry has the expected value (+/- 2D). No metal is transferred to the gas phase by the laser beam merely by mixing the peptide and iron(II), substantiating that the folding procedure is a necessary pre-requisite for protein formation. The Val-->Leu41 chemical mutant has also been synthesized and behaves in a closely similar fashion.

Amino Acid Sequence↗

PubMed1992

Induction of polyclonal antibodies to the S1 subunit of pertussis toxin by synthetic peptides coupled to PPD: effect of conjugation method, adjuvant, priming and animal species.

Two peptides, designated L and K, covering a sequence near the NH-terminal end of the S1 subunit of pertussis toxin (PT) were conjugated to the PPD (purified protein derivative) of M. tuberculosis by either glutaraldehyde (GLUT) or succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) and N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) and injected into groups of mice and guinea pigs. Initially, the effect of priming the animals with BCG vaccine and the use of aluminium hydroxide as adjuvant for the anti-peptide antibody response was studied. The group of BCG-primed mice immunized with adsorbed peptide conjugates showed the highest anti-peptide conjugate antibody response. Based on this finding, groups of BCG-primed mice were immunized four times with either adsorbed peptide L-GLUT, peptide L-SMCC/SPDP or peptide K-SMCC/SPDP conjugates and the fine peptide specificity as well as the PT and S1 cross-reactivity was investigated in ELISA. Mice immunized with peptide L-GLUT showed a significant antibody response to the homologous conjugate, only, whereas the group injected with the peptide L-SMCC/SPDP conjugate gave a significant response to both peptide K and L conjugated by the SMCC-SPDP method. Likewise, mice immunized with the peptide K-SMCC/SPDP conjugate reacted with the homologous and peptide L-SMCC/SPDP conjugate, although only the response to the former conjugate was significantly greater than the response to PPD. All groups showed a strong anti-PPD response. The anti-PT/S1 cross-reactivity of the antisera varied considerably within each group but was found to be highest in the peptide L-GLUT-immunized animals. The results of the present study not only stress the importance of BCG priming and use of aluminium hydroxide adjuvants for the immunogenicity of the peptides in question but also point to the specificity of the conjugation methods employed as low cross-reactivity between the anti-peptide L-GLUT and L-SMCC/SPDP antisera was noted. Moreover, it appeared that the choice of conjugation method may have an effect on the ability of the peptide conjugates to induce an antibody response cross-reacting with the native protein.

Adjuvants, Immunologic↗

PubMed1992

Identification of human T-cell epitopes on the S4 subunit of pertussis toxin.

Ten adult humans were vaccinated with the Japanese acellular pertussis vaccine JNIH-3, containing detoxified pertussis toxin (PT), formaldehyde, and filamentous hemagglutinin. The vaccination induced a specific antibody response to PT and filamentous hemagglutinin, and a Western blot (immunoblot) analysis of the antibody response to PT revealed antibodies to PT subunits S1, S2, S3, S4 and S5. The response of peripheral lymphocytes to PT was assessed in an in vitro proliferation assay. A proliferative response to detoxified PT and PT dimers S2-S4 and S3-S4 was found, and it was further demonstrated that the proliferative response to detoxified PT and dimer S2-S4 was mediated by T cells of the CD4+ phenotype. The specificity of the proliferative response to subunit S4 was analyzed with a range of synthetic peptides synthesized on the basis of the primary sequence of subunit S4. The proliferative response to the peptides revealed two major and one minor T-cell epitope located in the NH2-terminal end of subunit S4.

Adult↗

PubMed1992

Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein: evidence for protection of individuals living in a holoendemic area of Liberia.

A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155/RESA) (EENV)6 were examined in 423 individuals (age range 30 days-78 years) living in a malaria holoendemic area of Liberia. In the 5-9-year-old age group, subjects with anti-GLURP489-1271 antibody concentrations greater than the mean value of the group had lower parasite densities than those with low antibody concentrations (P = 0.0151). High levels of anti-GLURP899-916 antibodies did not correlate with low parasite densities. However, high levels of anti-(EENV)6 antibodies were associated with significantly lower parasite densities in the 2-4-year-old age group (P = 0.0189). There was no correlation between the anti-GLURP489-1271 and anti-(EENV)6 antibody responses. The data provide indirect evidence for a protective role of antibodies reacting with recombinant GLURP489-1271 as well as with the synthetic peptide (EENV)6 from the Pf155/RESA.

Adolescent↗

PubMed1991

On the mechanism of kidney stone disintegration by acoustic shock waves.

In the present study we have, by theoretical and experimental investigations, especially concentrated on the importance of acoustic streaming, transient cavitation and microstreaming in the fluid close to the stone. Artificial stones, round stones 20 mm in diameter made of Plaster of Paris or rectangular flat stones, 25 x 25 x 15 mm, were suspended in a water bath at the focus of an EDAP LT01 lithotripter. "Unprotected" stones were disintegrated while stones surrounded by a layer of silicone showed no or very small disintegration. For successful destruction of the calculus, it seems to be essential that the stones are surrounded by a liquid, i.e., water.

Humans↗

PubMed1991

Measurements of ultrasonic fields with optical diffraction tomography.

This article describes a light diffraction technique that allows a measurement of ultrasonic pressure and phase in the cross-section of an ultrasonic beam. The light diffraction measurements are based on the Raman-Nath model of ultrasonic continuous-wave light diffraction. The diffracted light intensity can be expressed as an integration of sound pressure along the light path. This integration is analogous to the integration of the absorption coefficient in x-ray tomography. Tomography algorithms can be employed on the light measurement data to calculate the pressure and phase in a measuring plane perpendicular to the ultrasound propagation vector. The reconstruction of the measurement plane is done with an implementation of an algebraic reconstruction technique (ART). Satisfactory results are obtained with 10 projections. The measurement method is applicable up to Raman-Nath parameter values of 2.3. The experimental results are compared to miniature PVDF hydrophone measurements.

Algorithms↗

PubMed1991

Cell surface hydrophobicity and electrokinetic potential of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus.

Laboratory strains and fresh isolates of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus were examined for cell surface hydrophobicity and for electrokinetic properties under different experimental conditions. Fresh isolates of A. actinomycetemcomitans and H. aphrophilus were hydrophobic. Laboratory strains of A. actinomycetemcomitans were 20-30% less hydrophobic than fresh isolates. No difference was observed between laboratory and fresh isolates of H. aphrophilus. The pH of the suspending buffer, growth phase or incubation atmosphere did not significantly affect the hydrophobicity of the 2 species, whereas agar cultures of H. aphrophilus were less hydrophobic than broth cultures. All A. actinomycetemcomitans strains treated with sterile filtered saliva showed a concentration-dependent decrease in hydrophobicity of at most 30%. H. aphrophilus strains were not affected by the same treatment. Laboratory strains of H. aphrophilus were more negatively charged than A. actinomycetemcomitans, whereas fresh isolates of the 2 species exhibited similar surface charge. In the presence of saliva the mean cell surface charge of laboratory strains decreased by 56% for A. actinomycetemcomitans and by 73% for H. aphrophilus. The results indicate that the 2 species differ in expression of cell structures accounting for hydrophobicity and surface charge and that environmental factors might differently influence the physical properties of the two species analyzed.

Aggregatibacter actinomycetemcomitans↗

PubMed1991

Digitizing 35 mm colour slides for computerized general image handling in ophthalmology.

Standard personal computers with appropriate graphic user interfaces can now be configured for work with near photographic quality colour image handling. Advantages and limitations of digitized colour image work, including cost considerations, are discussed in relation to some common ophthalmic photography situations. Practical methods are briefly described. Future developments are outlined, particularly methods for direct acquisition of high quality colour images and image compression/reduction.

Computer Systems↗

PubMed1991

Peroxide chemistry of triaryl-substituted imidazoles. Fenflumizole, a non-steroidal, anti-inflammatory agent.

Fenflumizole, [2-(2,4-difluorophenyl)4,5-bis(4-methoxyphenyl)imidazole] is a nonsteroidal, anti-inflammatory analgesic. It reacts quantitatively with 1O2 forming 2-(2,4-difluorophenyl)-4-hydroperoxy-4,5-bis(4-methoxyphenyl)imidazole in a reversible reaction. In ethanol solution at ambient temperatures, the peroxide regenerates parent fenflumizole and 1O2 together with minor quantities of other products. The structures of those products point to the intermediacy of a 1,3-endoperoxide and a dioxetane. These observations may be relevant to the biological activity of fenflumizole.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1990

The role of fragment X polymers in the fibrin enhancement of tissue plasminogen activator-catalyzed plasmin formation.

When thrombin-mediated fibrin formation and tissue plasminogen activator (t-PA)-mediated fibrinolysis proceed in dynamic interaction, desA-(desB beta 1-42)-fragment X polymers are shown to be the predominant fibrin derivatives present during the rapid second phase of Glu1- and Lys78-plasminogen activation. To further investigate the effect of this intermediate, a method was developed for the production and purification of fibrinogen-derived desA-(desB beta 1-42)-fragment X, deprived of both COOH-terminal A alpha-chains, but still capable of thrombin-mediated polymerization. DesA-(desB beta 1-42)-fragment X polymer was compared to intact fibrin with regard to its stimulatory effect on Glu1-, Lys78-, and Val443-plasminogen activation, and its binding of Glu1- and Lys78-plasminogen. Pure fragment X polymer gave rise to a biphasic activation pattern like that of fibrin, demonstrating similar kinetics of rapid phase activation. The dissociation constant for the binding of plasminogen to the effector decreases by a factor of 14, and the stoichiometry increases by a factor of 2 upon plasmin-catalyzed cleavage of both native Glu1- to Lys78-plasminogen, and fibrin to fragment X polymer. We conclude that desA-fibrin protofibril formation is sufficient to initiate fibrin enhancement of t-PA-catalyzed plasminogen activation, and that optimal stimulation depends on further plasmin-mediated modification of the fibrin effector to desA-fragment X-related moieties. Optimal stimulation is dependent on the presence of the kringle 1-4 domains of plasminogen and probably results from altered and increased binding of both plasminogen and t-PA to the modified effector.

Amino Acid Sequence↗

PubMed1990

Dot immunobinding and immunoblotting of picogram and nanogram quantities of small peptides on activated nitrocellulose.

Nitrocellulose was activated with divinyl sulfone, a spacer of ethylenediamine, and glutaraldehyde. The aldehyde groups on the activated nitrocellulose, Nit-CHO, were stable through one month at 4 degrees C. Peptides were attached to the membrane by reaction of the amino group with the free carbonyl, forming peptide bonds. The decapeptide angiotensin I (AI), the octapeptide angiotensin II (AII), angiotensin analogues, Met- and Leu-enkephalin (Met-E and Leu-E) were tested on the membranes with specific rabbit antibodies (sRaAb) against the peptides, and visualized by horseradish peroxidase conjugated anti-rabbit antibody (HRP-anti-RaAb). With this technique AII could be detected with a sensitivity of 20 pg/cm2 and AI by 500 pg/cm2. Substitution of Ala7 for Pro7 in AI and AII caused a marked reduced binding of anti-AI and antid-AII antisera, respectively, and it completely abolished crossreactivity of anti-AI with Ala7-AII as well as anti-AII with Ala7-AI. Peptides from the gp41 and gp36 antigens corresponding to the sequence aa596-618 of the human immunodeficiency viruses type 1 and 2, HIV-1 and HIV-2, were tested on Nit-CHO with two human sera from infected patients. The serological reactions were specific for both the HIV-1 and HIV-2 peptide, respectively. This indicated that the technique could be exploited for serological testing of humans. Separation of peptides by high performance thin layer chromatography (HPTLC) and identification by immunoblotting was demonstrated with angiotensin analogues. After separation by HPTLC on silica aluminium plates the peptides were electrotransfered by semidry electroblotting on Nit-CHO, followed by specific antibody overlays and developed as for the dot immunobinding technique. This combined method enabled us to differentiate between closely related peptide analogues and it improved the sensitivity of peptide detection 100-1000 fold as compared to visualization by quenched fluorescence on chromatography plates.

Angiotensin I↗

PubMed1990

Covalently linked peptides for enzyme-linked immunosorbent assay.

A general method is described, by which synthetic peptides are covalently linked via their carboxyl group to microtiter plates (CovaLink) for enzyme-linked immunosorbent assay (ELISA). Plates were prepared by this method with an angiotensin II peptide and with an HIV-2 peptide and attachment detected by rabbit anti-angiotensin serum and with a positive serum from an HIV-2-infected patient, respectively, using the common ELISA procedure in the last steps. The method is simple to perform, it constitutes an alternative to the common ELISA method, and eliminates the risk of inadvertent loss of peptide during the procedure. The method is highly reproducible and has a high sensitivity. It may be used for either antigen or antibody detection.

Angiotensin II↗

PubMed1990

Gastrointestinal complications after cardiac transplantation. Potential benefit of early diagnoses and prompt surgical intervention.

Acute gastrointestinal (GI) illnesses are unusual but potentially fatal complications following cardiac transplantation. A retrospective study was performed to analyze the frequency, etiology, and severity of GI complications and the potential impact of early diagnosis and prompt surgical intervention when appropriate. Between 1981 and July 1, 1988, 31 GI complications (pancreatic, 6; colonic, 6; gastroduodenal, 6; biliary, 5; esophageal, 3; appendiceal, 2; hernia, 2; and splenic, 1) occurred in 26 patients undergoing 32 cardiac transplants. Complications were most common (14 of 31 patients, 45%) within the first 30 days after transplantation. Seventeen GI complications were treated medically (2 deaths), 2 with elective surgery and 12 with emergent operations (3 deaths). The overall mortality rate was 16%. All patients who underwent emergent operations within 3 days of onset of symptoms survived; the mean interval of onset between symptoms and operation in the nonsurvivors was 10 +/- 3.8 days. We infer that among patients requiring urgent surgical intervention, successful outcome is enhanced by intense surveillance for early symptoms, prompt diagnostic evaluation, and early surgical intervention.

Acute Disease↗

PubMed1989

Peritoneovenous shunt for intractable ascites of hepatic, nephrogenic, and malignant causes.

A retrospective analysis of 54 patients with a peritoneovenous shunt inserted to control massive ascites refractory to conventional medical treatment is presented. The cause of ascites was hepatic in 29 patients (Group 1, 54 percent), malignant in 13 (Group 2, 24 percent), and nephrogenic in 12 (Group 3, 22 percent). The peritoneovenous shunt failed in 11 patients (20 percent): 6 in Group 1, 3 in Group 2, and 2 in Group 3. Shunt outflow obstruction (thrombosis) was the principal cause. Systemic sepsis in five patients and variceal hemorrhage in three were the factors responsible for most of the deaths (22 percent). Of the 42 patients who survived operation, the peritoneovenous shunt was effective in controlling the massive ascites in 37 (86 percent). Eight patients (15 percent), four with hepatic and four with nephrogenic ascites, survived 3 years or more without ascites. Removal of at least 50 to 70 percent of ascitic fluid at the time of shunt insertion was considered an important factor in decreasing morbidity and mortality. A peritoneovenous shunt can be effective for a long-term period in controlling massive ascites with an hepatic or nephrogenic cause in a selected group of patients; however, in patients with malignant ascites, although the benefit was substantial in half, the survival period did not exceed 6 months.

Adult↗

PubMed1989

Hepatic resection of metastasis from colorectal carcinoma. Morbidity, mortality, and pattern of recurrence.

To identify the factors that determine the morbidity and mortality of liver resection of metastases from colorectal carcinoma and the variables that may influence the pattern of recurrence, the survival time and the disease-free rate, a univariate and-multivariate statistical analysis (30 variables using Student's t-test, Fischer's exact test, and chi square test) was performed. Intraoperative blood loss of greater than 3500 ml was found to be a significant risk factor to developing postoperative complications (p less than 0.05 by x2). After a mean follow-up of 25.8 months, 26 of the 35 patients studied (74%) had recurrent disease. In the univariate analysis, the following factors appear to be reliable predictors of early recurrence: poor degree of differentiation of the primary colorectal tumor, the presence of multiple liver metastases, the male gender, and the presence of tumor at the margin of the resected hepatic tissue (p less than 0.05). However, only the latter two factors appeared also to affect the survival time and the disease-free rates at 2 years after hepatic resection of metastases (p less than 0.05). In the multivariate analysis (factors tested simultaneously), presence of an advanced liver metastatic disease (Stage II or III) consistently indicated early recurrence and poor survival (p less than 0.005). The liver was the most common site of recurrence as the sole site of recurrence (54%) or in combination with other sites (88%)--followed by the lungs (31%) and the site of colonic resection (8%). Twenty-nine (83%), 14 (40%), and nine (26%) patients survived without recurrent disease at 1, 2, and 3 or more years, respectively, after hepatic resection of metastases. In six patients (17%), no significant palliation was noted, primarily because of early recurrence (less than 6 months). From this data, resection of hepatic metastases from colorectal cancer appears to offer a realistic therapeutic option to a selected group of patients, but only if the resective procedure can be performed with an operative mortality rate of less than 5%.

Adenocarcinoma↗

PubMed1989

The T-lymphocyte proliferative response to synthetic peptide antigens of defined secondary structure.

Immunodominant sites in proteins recognized by T lymphocytes are segments consisting of at least 7-8 amino acids. It has previously been proposed that these sites in proteins are alpha-helical and amphipatic structures. We synthesized and investigated the immunogenicity of three synthetic peptides (MP7, MP8, and MP9), each consisting of the same 15 amino acids, but differing with respect to sequence. Based on information analysis and circular dichroism measurements, MP7 was shown to have an alpha-helical secondary structure and, based on previously assigned hydrophilicity indices, was also strongly longitudinally amphipatic. MP8 also was conformed as an alpha-helix, but was amphipatic in the sense that the N-terminal half of the molecule was hydrophilic and the C-terminal half hydrophobic. MP9 had neither an amphipatic nor alpha-helical structure. All three peptides were immunogenic in some strains of mice but none was immunogenic in all strains. This supports other studies concluding that amphipaticity per se is neither a necessary nor sufficient requirement for immunogenicity of a peptide. On the other hand, the present experimental data suggest that longitudinally amphipatic alpha-helical peptides may function better as T-cell determinants than the other peptides investigated.

Amino Acid Sequence↗

PubMed1989

In vivo chemotaxis evoked by Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus.

The chemotaxis-evoking capacity of 5 Actinobacillus actinomycetemcomitans and 5 Haemophilus aphrophilus strains were studied in a tissue cage model in rabbits. A significant increase of the total number of polymorphonuclear leukocytes was induced in the tissue cage fluid by both viable and killed bacteria, reaching a maximum after 12-24 h. In parallel, the proportion of viable/non viable leukocytes increased. The leukocyte counts declined during the following 24-48 h in all chambers except in those inoculated with viable cells of H. aphrophilus. The H. aphrophilus strains survived the 72 h experiment while A. actinomycetemcomitans decreased to undetectable levels within 24-72 h. Lactate dehydrogenase and lysozyme activities in cage fluid increased in all but the uninoculated chambers. Viable bacteria induced higher activities of the enzymes than killed ones. It is concluded that both species of bacteria exhibit similar chemotaxis evoking properties. A strain dependent ability to induce release of leukocyte-associated enzymes exists.

Actinobacillus↗

PubMed1989

Short- and long-term effectiveness, morbidity, and mortality of peritoneovenous shunt inserted to treat massive refractory ascites of nephrogenic origin analysis of 14 cases.

The experience with 14 patients with end-stage renal disease (ESRD), 13 of them maintained on chronic hemodialysis (x 20.4 months +/- 2.9 SEM) and one following successful renal transplantation, underwent placement of a peritoneovenous shunt (PVS) for refractory ascites that had been present before insertion from two to 15 months (x 5.3 +/- 0.8 SEM). A "specific" cause for the ascites could not be identified in any of the 14 patients. The ascites was an exudate in every patient (protein content greater than 3.5 gm/dl). Twelve patients (86%) obtained significant relief of the discomfort and all effects of the ascites, and objective clinical improvement persisted for at least six months. Nine patients (75%) survived one year and six (50%) survived three or more years. Three patients (21%) had recurrence of ascites because of shunt malfunction; however, two of them were successfully treated with placement of a second shunt. Eight (57%) patients have died since the onset of their ascites (x 14.1 months +/- 3.5 SEM); one death was attributable to PVS placement, while the other seven deaths were due to complications of their ESRD. Insertion of a PVS is an effective therapeutic alternative to palliate the discomfort and ill effects of massive nephrogenic ascites that is often refractory to hemodialysis with ultrafiltration.

Adult↗