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Biomedical subjects

S Heinz

Publications and source records attributed to S Heinz.

11 recordsLinked to original sources

Rho(0) meson production in the pp-->pppi(+)pi(-) reaction at 3.67 GeV/c.

Total and differential cross sections for the exclusive reaction pp-->pp rho observed via the pi(+)pi(-) decay channel have been measured at p(beam)=3.67 GeV/c. The observed total meson production cross section is determined to be (23.4+/-0.8+/-8) mu b and is significantly lower than typical cross sections used in model calculations for heavy-ion collisions. The differential cross sections measured indicate a strong anisotropy (approximately cos(theta(CM)(rho)) in the rho(0) meson production.

Journal Article↗

Characterization of MAX.3 antigen, a glycoprotein expressed on mature macrophages, dendritic cells and blood platelets: identity with CD84.

MAX.3 is a monoclonal antibody that preferentially reacts with mature macrophages (MAC), monocyte-derived dendritic cells, megakaryocytes and platelets. In this study, we describe the characterization, purification and identification of the MAX.3 antigen. Immunoprecipitation and SDS/PAGE revealed different molecular masses of MAX.3 antigen in MAC (60-90 kDa) and platelets (58-64 kDa), whereas a similar size (45 kDa) was observed in both cell types after digestion with N-glycosidase F. Lectin affinity and sequential treatment with different glycosidases suggests complex type glycosylation of MAX.3 antigen in MAC and hybrid type glycosylation in platelets. Amino acid sequencing led to the identification of a corresponding cDNA clone and showed its identity to the sequence of the CD84 antigen, a member of the CD2 family of cell surface molecules. MAX.3/CD84 was further studied by immunohistochemistry and a variable expression was found on tissue MAC, confirming this antigen to be mainly a marker for MAC in situ.

Amino Acid Sequence↗

A Shotgun Model for Gamma-Ray Bursts.

We propose that gamma-ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma-ray emission is produced in the shocks these bullets drive into the surrounding medium. The short-term variability seen in GRBs is set by the slowing-down time of the bullets, while the overall duration of the burst is set by the lifetime of the central engine. A requirement of this model is that the ambient medium be dense, consistent with a strong stellar wind. The efficiency of the burst can be relatively high.

Journal Article↗

Hydrogen peroxide for prevention of bacterial growth on polymer biomaterials.

BACKGROUND: Despite widespread use of potent antibiotics, infections of artificial implants and catheters are of increasing concern. We tested whether local treatment with 3% hydrogen peroxide (H2O2), long known as an inexpensive wound disinfectant, could prevent or reduce bacterial growth on polymer biomaterials. METHODS: Two-centimeter-long pieces of polyurethane and silicone tubing were contaminated with a standardized solution of Staphylococcus epidermidis (10(5)/mL) and then rinsed and wiped with saline (0.9%) solution. Bacterial growth was assessed after incubation at 37 degrees C for 24 hours. Bacterial colonies were compared for the following treatments: wiping only with saline; wiping with 1.5%, 2%, or 3% H2O2; pretreating biomaterials with 3% H2O2 and subsequent contamination for 2 and 4 hours without treatment after contamination; and contamination of tubings 1 month after pretreatment with 3% H2O2. The effect of 3% H2O2 was also assessed on contamination with Escherichia coli. RESULTS: Bacterial growth was reduced by more than 99% when the contaminated tubes were treated with 3% H2O2 compared with saline control (p < 0.001). Lower concentrations of H2O2 were less effective. The length of the contamination period had no influence on the effectiveness of H2O2 when used on polyurethane but did with silicone tubings. Pretreatment with H2O2 1 month before contamination still reduced bacterial growth rate by 90% on polyurethane and by 75% on silicone tubings. Comparable effects on bacterial growth rate were observed for staphylococci (-90%, p < 0.001) and escherichiae (-90%, p < 0.001). CONCLUSIONS: Local treatment with 3% H2O2 significantly reduced bacterial growth on polymer biomaterials even for 1 month after treatment. This finding might influence clinical strategies of prevention of foreign body infection.

Anti-Infective Agents, Local↗

Does reducing capacitance have potential for further miniaturisation of implantable defibrillators?

OBJECTIVE: To determine whether considerably smaller capacitors could replace 125 microF capacitors as the standard for use in implantable defibrillators. METHODS: Measured energy, impedance, voltage, and current delivered were compared at defibrillation threshold in 10 mongrel dogs for defibrillation using 75 microF and 125 microF capacitors alternated randomly. Defibrillation was attempted with biphasic shocks of comparable tilt between an endocardial lead in the right ventricular apex and a "dummy" active can of an experimental implantable device placed in the subpectoral position. RESULTS: A reduction of capacitor size of 40% was associated with an increase in voltage of 21% and in current of 22%. With a 65% tilt, no significant differences were found between the two capacitances with respect to the impedance or energy required for defibrillation. CONCLUSIONS: Multiple advances in electrode material, electrode configuration, shock morphology, and shock polarity have reduced defibrillation energy requirements. Smaller capacitors could be used in implantable cardioverter/defibrillators without a major decrease in effectiveness.

Animals↗

Pilot study of intravenous magnesium sulfate in refractory cardiac arrest: safety data and recommendations for future studies.

UNLABELLED: Recent case reports have evidenced a temporal association between administration of i.v. magnesium sulfate (M) and resuscitation from prolonged cardiac arrest refractory to standard (S) ACLS attempts. However, speculation has arisen that M as a vasodilator, may decrease aortic diastolic and coronary perfusion pressure (CPP), aortic systolic and cerebral perfusion pressures (CePP), which may decrease resuscitation rates and neurologic recovery, as compared to standard ACLS alone (SA). OBJECTIVE: To resolve positive beginning evidence vs. negative theory, we conducted a pilot study of M+S vs. SA in refractory cardiac arrest on resuscitation rates (% R, return of stable pulses > 30 min without CPR, first in-hospital cardiac arrest > 5-min duration) and neurologic recovery/survival to hospital discharge (SHD). METHODS: All patients from 1 January 1990-31 December 1991 at Rose Hospital, in cardiac arrest refractory to S through the first epinephrine dose (including 3 defibrillation attempts with pulseless VT/VF) were included in the data analysis, except: (1) patients with trauma, known poisoning, < 18 years, pregnancy excluded; (2) Standard ACLS alone patients with cardiac arrest < 5-min duration were not included in the SA comparison group, because the shortest cardiac arrest time before i.v. MgSO4 administration in the M+S group was 5 min. M+S (N = 29) and SA (N = 33) groups were also comparable on mean age (72-73 years) in this open-label prospective case-matched control group study. RESULTS: SHD rates were nearly equivalent between M+S (5.2%) and SA (4.5%). Complete or partial neurologic recovery, as best neurologic status post-R, occurred in 21% (6/29) M+S patients vs. 9% (3/33) SA (P = 0.17), even though cardiac arrest time on the study code call for resuscitated patients averaged shorter with SA (14.2 min) than M+S (19.8 min). M was frequently administered late in the resuscitation attempt--code call to M administration averaged 16.5 min (< 10 min in only 4/28 patients). A trend toward increased % R with M was evidenced: 21% (7/33) SA vs. 35% (10/29) M+S (P = 0.21). A temporal association between M administration and first return of spontaneous circulation (ROSC) was also documented in 4 of 10 M+S patients (pulseless electrical activity (3)/pulseless VT (1)), who had first ROSC/R occur within 0.5-2.25 min following first i.v. M bolus delivery, after 11-30 min (mean = 20 min) of continuous pulseless rhythm refractory to standard ACLS. All M+S resuscitations occurred within the dose range 2.5-5 g (i.v. push): 3/6 (50%) and 7/13 (54%) R occurred with 1-3 g and 4-5 g MgSO4, respectively (at least 11/13 patients had peripheral i.v. delivery with 4-5 g M). Analyzing post-ROSC hypotension proved important, as 50% of pts with first recorded systolic BP post-ROSC < 90 mmHg were resuscitated vs. 83% with > 90 mmHg (P = 0.10). A trend toward increased post-ROSC hypotension was evidenced with i.v. MgSO4: Recorded first or second systolic BP < 90 mmHg post-ROSC occurred in 66% of M+S vs. 42% of SA patients. All 3 M+S patients having a wide open i.v. levophed infusion as vasopressor support, started immediately post-ROSC/i.v. MgSO4 with systolic BP < 90 mmHg and continued at least 15 min (titrating to a systolic BP approximately 110 mmHg), had a temporal association between M delivery and R after 14-30 min of continuous pulselessness refractory to S. CONCLUSION: Human research determining whether i.v. MgSO4 increases long-term survival from refractory cardiac arrest should be vigorously pursued, as it is safe to proceed given the above described considerations.

Aged↗

Long-term treatment with SMS 201-995 in resistant acromegaly: effectiveness of high doses and continuous subcutaneous infusion.

Seventeen patients (8 women and 9 men) resistant to all other forms of therapy were treated with the somatostatin analogue SMS 201-995 (octreotide, Sandostatin). The duration of treatment ranged from 1 to 5 years. Mean GH levels of only 4 patients were suppressed under 5 micrograms/L during an 8 h serum profile with the standard dose of 0.1 mg 2 or 3 times daily. This standard dose suppressed mean GH levels in 10 other patients more than 50% of baseline, but for optimal effect higher doses up to 1.5 mg, 4 daily injections or continuous subcutaneous infusion (CSI) were needed. Octreotide had no influence on GH secretion in 3 patients. Suppression of mean GH levels under 5 micrograms/L was achieved in 10 patients. Normalization of insulin-like growth factor I (IGF-I) occurred in only 5 patients. Altogether, therapy with SMS 201-995 reduced GH levels from 23.8 +/- 32.2 micrograms/L (mean +/- SD) to 6.7 +/- 5.0 micrograms/L by 71.8% and IGF-I levels from 7.9 +/- 3.1 U/ml to 3.2 +/- 1.6 U/ml by 59.5%. We conclude that 1) treatment with SMS 201-995 in patients resistant to other forms of therapy may be less successful than previously reported for heterogenous groups of patients; 2) the dose regimen must be adapted to the individual patient for optimal effect and most of our patients needed higher doses than 300 micrograms daily; 3) 4 or maybe more daily injections or CSI seem to be most effective; and 4) in a minority of patients SMS has no influence on GH-secretion.

Acromegaly↗

Conservative care of low back pain with emphasis on isokinetic exercise.

Twenty patients with complaints of low back pain were treated using a sports medicine approach to rehabilitation with isokinetic back exercises for therapy and testing. Nineteen of the 20 patients were returned to regular work, and the remaining patient was able to resume light work. Physical therapy averaged 5.4 weeks in patients without a disc problem. As extensor strength increased in concurrent testing, pain symptoms decreased. A suggestion of an end point to physical therapy was noted, i.e., no further increase in extensor strength on concurrent testing.

Adult↗

Quantitative effects of allogeneic small-bowel transplantation on nutrient digestion and on body protein balance as determined in vivo in rats.

Heterotopic and orthotopic small-bowel allotransplantation was carried out in Wistar rats using grafts reduced to one-half of the original length. Portocaval venous anastomoses and intestinal end-to-end anastomoses were performed. Animals either with complete or with partially reduced native small-bowel served as control. In a total of 51 rats, 88 quantitative in vivo measurements of apparent digestion and absorption of dietary dry matter, organic matter, energy, protein, fat, total ash, and glucose were carried out. Body protein retention was calculated from intake and losses with feces and urine. The digestion trials comprised 8 days of adaptation and 10 days of continual recording of nutrient balance data. In experiments 1 and 2, digestibility coefficients were obtained before and after transplantation within the same animals, untreated or initially treated with cyclosporine A after surgery. Similar groups of rats untreated, with partial resection and with transplantation of the small-bowel, followed by temporary cyclosporine treatment, were used in experiment 3. In experiment 4, rats with transplanted intestines from experiments 1 and 2 were subjected to a further digestion trial 4 to 6 months after the respective first trial. With transplantation of the small intestine, apparent digestion and absorption of nutrients, as well as protein retention, tended to be lower. Significant depression occurred in the digestion of fat and ash. In long-term survivors all parameters decreased further. The adverse effects on fat and ash digestion seemed to be pronounced when rejection occurred. Fecal fat excretion might therefore be an indication of dysfunction of small-bowel grafts. Digestion was less imparied if cyclosporine was applied, and part of the effects on digestion and protein balance could be attributed to the shortened bowel.

Animals↗

A consumer and media viewpoint.

The future of the nuclear community will not resemble the past. Suddenly gone are the years of blind public trust, cheers for building the bomb that ended a world war, and the unquestioned alliance of patriotism and Pu. Awakened by the radioactivity cloud from Chernobyl and recent revelations of major releases during Hanford's early years, the public is demanding to play a part in its own future in suddenly jam-packed hearings. After four decades, nuclear pioneers should consider that a technology fashioned largely in the vacuum of war-driven secrecy is now being judged--fairly or not--alongside the rather unforgiving measures of present-day politics, economics and morality. The spiral of distrust may continue without a semblance of the following remedies. (1) The press and the public need to become better educated in radiation basics to start making more informed decisions on multi-billion-dollar issues. (2) Because reasoned public discussions of anything nuclear is at an impasse, supporters and critics of nuclear activities should spend less time trying to discredit their opponents and more time trying to understand why they think as they do. (3) The radiation-protection community should welcome scrutiny for one simple reason: no other way exists to regain public trust and respect.

Community Participation↗