Systematic Review of Literature Citing the ISCHEMIA Trial

PURPOSE OF REVIEW

Optimal therapy for patients with chronic coronary artery disease (CCD) has long been a topic under investigation and a subject of debate. Seeking to clarify appropriate management, the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial compared medical management versus coronary angiography for patients with stable ischemic heart disease. Its reception in the medical community has been met with both acclaim and criticism. In light of such disparate views of this trial, a systematic review of the literature citing the ISCHEMIA trial was performed.

RECENT FINDINGS

All articles citing the ISCHEMIA trial on PubMed as of July 21, 2023, were compiled and underwent qualitative analysis. A total of 430 articles were evaluated; 109 (25.3%) did not offer substantial commentary on ISCHEMIA and cite it as background evidence for further study. Of the commentary articles, the majority (224, 52.1%) gave balanced, honest appraisals of the ISCHEMIA trial. A total of 46 (10.7%) strongly praised the trial while another 39 (9.1%) were strongly critical of the results. Almost three-quarters of the literature citing the ISCHEMIA trial was commentary in nature, with roughly equal distribution across the spectrum of praise and criticism. Despite being one of the largest studies on CCD and coronary revascularization ever conducted, the impact of ISCHEMIA on the cardiology community appears to be mixed.

P-722 Ending the anonymity of egg donors in shared donation programs could reduce the number of participants

Study question

Loss of egg donor anonymity could affect shared donation programs in Brazil?

Summary answer

Yes. Approximately 20% of the women who participated in this study would drop out of the program, especially those with higher incomes.

What is known already

The Brazilian Federal Council of Medicine seems to be increasingly flexible with regard to maintaining mandatory secrecy on the identity of donors. The resolution regarding assisted reproduction techniques, approved in 2021, concerns the possibility of donation between family members, up to fourth degree relatives. The possibility to know and have access to this identity or even the search for half-brothers can be a reality in many countries for children born through access to reproductive technology but the opinion or behaviour of this population about the presence or absence of anonymity is limited to a few studies.

Study design, size, duration

Women (n = 800) who applied for enrolment in the shared egg donation program at a private IVF clinic were invited to participate in an electronic survey developed using the online Survio® tool. The invitation to participate was sent by email from June to November 2021. 279 women (34.8%, 20-35 years) responded to the survey.

Participants/materials, setting, methods

The information was obtained through questioning and gaining information about: socioeconomic profile of the donors, their motives, ambivalence in relation to the sharing of eggs and feelings about a possible end of anonymity. Thereafter, answers given to 10 specific questions were recorded. Furthermore, a correlation analysis was performed to assess the relationship between acceptance of the end of donor anonymity and various study parameters.

Main results and the role of chance

Approximately 61% of patients would want to become egg donors for two reasons: to reduce IVF costs and to help another woman. However, significantly younger women want to be part of the egg donation program just to reduce their treatment costs (P < 0.05). Approximately 71% of women do not want any contact with the child born from their eggs; 69% of them would not like to meet the recipients and 75% would not like to meet the child, even if only the recipient had become pregnant. If donors lost a child, they would not even want to meet the child who was born with their donated eggs (76%).

Most participants also responded that they would be in the program even if the anonymity was not maintained (80%). However, women with higher income would drop out of the program if donor anonymity was not maintained (56.3%) compared to women with lower income (13.5%;P < 0.001).

Limitations, reasons for caution

Confounding variables related to the male partner's opinion cannot be excluded. Studies with larger samples are needed to confirm these findings.

Wider implications of the findings

A possible end to the anonymity of egg donors in Brazil would pose numerous challenges to the current practice of gamete donation. These concerns give rise to a broad discussion in society about how best to safeguard and promote the interests of donor-conceived children and protect the rights of donors.

Trial registration number

Not applicable.

P-535 Preimplantation Genetic Testing for Aneuploidy (PGT-A) for patients aged ≤ 37 years: Today, evidence-based medicine does not support its use. A meta-analysis

Study question

Do patients aged ≤37 years truly benefit from using PGT-A as an add-on to increase ongoing pregnancy rate (OPR)/live birth rate (LBR) in their first IVF/ICSI cycle?

Summary answer

The use of PGT-A is not superior to classic morphological embryonic selection to increase OPR/LBR in patients aged ≤37 years in their first IVF/ICSI cycle.

What is known already

The embryonic aneuploidies increase exponentially with advancing-maternal-age, ranging from 30-50% up to 37 years to 80% in women ≥42 years. Consequently, the use of PGT-A seems to be a useful add-on for patients with advanced-maternal-age, but not necessarily for young women undergoing their first IVF/ICSI cycle. Recent studies investigated the benefit of PGT-A, concluding that it was accompanied with lower OPR/LBR, when compared to conventional-cycles in women aged ≤37 years. However, the use of this add-on in IVF/ICSI cycles is increasing alarmingly. Furthermore, adding PGT-A in reproductive treatments is related with increased costs and limitations inherent to the test itself.

Study design, size, duration

A systematic review based on electronics searches of databases (PubMed/MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane database. Keywords: PGT-A; Morphological embryonic selection; ongoing pregnancy; live birth) up to December 2021 was conducted to identify randomised controlled trials (RCTs) comparing clinical outcomes of IVF/ICSI cycles with PGT-A versus Morphological embryonic selection. The primary outcomes were ongoing pregnancy and live birth rates.

Participants/materials, setting, methods

Seven RCTs were included as targets for data extraction and meta-analysis. Three studies reported on OPR and five reported LBR of patients who underwent their first IVF/ICSI cycle. Data were combined for meta-analysis using StatsDirect statistical software. Dichotomous data were expressed as Relative Risk(RR) with a 95% confidence interval(CI). The amount of heterogeneity was evaluated using Cochran’sQ and I2. Study data were combined using a Random-effects model. P-values <0.05 were considered to be statistically significant.

Main results and the role of chance

-Ongoing pregnancy rates (three trials): PGT-A group: 67.4% (485/720) versus morphological embryo selection group: 63.2% (460/728) with no statistically significant differences (RR = 1.11; 95% CI = 0.89–1.39; P=0.35)

-Live birth rate (five trials): PGT-A group: 58.9% (578/981) versus Morphological embryo selection group: 57.9% (585/1010) with no statistically significant differences (RR = 1.01; 95% CI = 0.81–1.26; P=0.91).

Table 1 shows the data.

Limitations, reasons for caution

The main limitation of this meta-analysis is the low number and heterogeneity of studies included. However, all of the included studies are randomised controlled trials, and the data were meta-analysed using Random-effects.

Wider implications of the findings

This meta-analysis brings to light a fundamental discussion currently, in which physicians and embryologists employ add-ons to improve clinical outcomes even without adequate scientific support.Medical practices are based on scientific evidence and Reproductive Medicine is not different. Therefore, at the moment, PGT-A should not be indicated for patients aged ≤37years.

Trial registration number

Not applicable

O-190 Endometrial compaction in artificial frozen-thawed embryo transfer cycles is associated with improvement in pregnancy outcomes: a meta-analysis

Study question

Does the decrease in endometrial thickness between the end of oestrogen phase and embryo transfer day (endometrial compaction) impact the pregnancy outcomes in frozen-thawed embryo transfer (FET) cycles?

Summary answer

The combined data indicated that cycles with endometrial compaction resulted in significantly higher ongoing pregnancy/live birth rate than cycles with no decrease in endometrial thickness.

What is known already

In FET cycles the monitoring of endometrial thickness was mostly concentrated at the end of the endometrium proliferation phase, while research on endometrial thickness in the luteal phase around the embryo transfer day was relatively rare. In addition, few studies have investigated the change in endometrial thickness after progesterone administration, and the conclusions are contradictory. Some studies included women who used hormone replacement therapy for endometrial preparation and showed that endometrial compaction (decreased thickness between the end of oestrogen phase and embryo transfer day) was associated with higher pregnancy rates. However, others reached different conclusions.

Study design, size, duration

A systematic review and meta-analyses was carried out to analyse the effect of endometrial compaction on FET cycle outcomes. The search strategy included online searching of databases (MEDLINE, EMBASE, The Science Citation Index, Google scholar, Cochrane Controlled Trials Register and OVID) up to December 2021. There was no language restriction and included grey literature. The following Medical Subject Headings and text words were used: frozen-thawed embryo transfer, hormonal preparation, endometrial thickness, endometrial compaction.

Participants/materials, setting, methods

Only cycles with artificial endometrial lining preparation (oestrogen-progesterone) and that compared outcomes of endometrial compaction cycles versus no endometrial compaction (no change/increased in endometrial thickness) cycles were considered. The primary outcomes were clinical pregnancy(CPR), miscarriage(MR) and ongoing pregnancy/livebirth (OPR/LBR) rates. The Breslow–Day-statistic, Q-statistic and I² (inconsistency) were used to determine the combinability of the trials. The random effects model was used for odds ratio(OR). The StatsDirect statistical software (Cheshire, UK) was used for data analysis.

Main results and the role of chance

Although endometrial compaction does not significantly affect CPR (OR:1.31[0.91-1.89],P=0.14) and MR (OR:1.18[0.87-1.59];P=0.27, it seems to be associated with a higher OPR/LBR (OR:1.54[1.12-2.13];P=0.007). Table 1 shows the data.

Limitations, reasons for caution

Some trials did not report clinical pregnancy or miscarriage rate. It could be associated with differences in the results. The retrospective nature and lack of standardisation of procedures across studies should be highlighted. Some analyses show high heterogeneity. Although statistically significant, the results in both arms are very close. 

Wider implications of the findings

The combined results support the change in endometrial thickness as an easy, low-cost, potential noninvasive marker of endometrial receptivity. However, additional trials are still needed.

Trial registration number

Not applicable

O-180 Body mass index (BMI) is not associated with ovarian response to gonadotropin during IVF/ICSI treatment: An evaluation of 4499 IVF/ICSI cycles

Study question

Is there an association between body mass index (BMI) and ovarian response in IVF/ICSI treatment?

Summary answer

BMI does not seem to be associated with the ovarian response to gonadotropin.

What is known already

Obesity is becoming an increasingly widespread health problem. Elevated BMI in patients who undergo assisted reproduction technology has been associated with higher doses of gonadotropins, higher risks of ovarian hyperstimulation syndrome, increased cancellation rates, and lower oocyte recovery compared to women with normal BMI. In addition, overweight and obese women submitted to IVF may present reduced rates of clinical pregnancy and live births and an increased miscarriage rate. However, population differences should be considered.

Study design, size, duration

This prospective cohort study included 4499 women who underwent IVF/ICSI cycles. Only one cycle per couple was considered. Inclusion criteria included normal karyotype, presence of two ovaries as observed by ultrasound examination, and no history of ovarian surgery, endometriosis, hydrosalpinx, infection, or endocrine disorders. Patients were stratified into four groups by BMI: <18.5 kg/m2 (underweight); 18.5-24.9 kg/m2 (normal weight); 25-29.9 kg/m2 (overweight); and ≥30 kg/m2 (obesity).

Participants/materials, setting, methods

The BMI values were associated with age, anti-Müllerian hormone (AMH) levels, antral follicle counts (AFC), total dose of FSH and LH, number of follicles and number of retrieved oocytes (total and metaphase II) of IVF/ICSI cycles. The statistical analyses for group comparisons were performed using t test, Mann–Whitney test and the Kruskal–Wallis test.

Main results and the role of chance

No statistically significant differences were observed between BMI groups regarding age, AMH levels, AFC, dose of gonadotropin used (FSH and LH), days of stimulation, number of follicles and number of retrieved eggs (total and metaphase II). Table 1 summarizes the results.

Limitations, reasons for caution

A possible limitation is the cross-sectional nature of the data. Differences in sample size between BMI groups may have influenced the results.

Wider implications of the findings

Against common sense in the literature, the results did not reveal a relationship between BMI and the ovarian response to gonadotropins. BMI as an additional tool in the individualization of ovarian stimulation protocols should be reviewed.

Trial registration number

Not applicable.

O-157 Female body mass index (BMI) influences pregnancy outcomes: An evaluation of 4349 IVF/ICSI cycles

Study question

Does female body mass index (BMI) impair pregnancy outcomes after IVF/ICSI cycles?

Summary answer

High BMI (overweight and obesity) and low BMI (underweight) are associated with decreased clinical pregnancy and live birth rates and an increased miscarriage rate.

What is known already

Obese women undergoing treatment for infertility may face problems, such as the need for higher doses of drugs to stimulate ovulation, oocyte morphological changes, reduction in fertilization and implantation rates, and embryo quality. Compared to women of normal BMI, obese women submitted to IVF may present reduced rates of clinical pregnancy and live births and an increased miscarriage rate. Regarding the effects of low BMI, unfavourable pregnancy outcomes and infertility problems have been described, but evidence is still scarce and conflicting.

Study design, size, duration

A prospective analysis was performed of 4349 couples who underwent IVF/ICSI treatment and fresh embryo transfer. Only one cycle per couple was considered. Exclusion criteria included abnormal karyotype, uterine defects, evidence of hydrosalpinx, infections, endocrine problems, coagulation defects or thrombophilia and autoimmune defects. Couples were stratified into four groups by female BMI: <18.5kg/m2 (underweight); 18.5-24.9kg/m2 (normal weight); 25-29.9kg/m2 (overweight); and ≥30kg/m2 (obesity). Clinical pregnancy, miscarriage and live birth rates were the outcomes analysed.

Participants/materials, setting, methods

Variables such as age, duration/type of infertility, previous embryo transfers, aetiologies, endometrial thickness, type of ovarian stimulation, and number/quality/development stage of embryo transferred were included as potential confounding factors. For group comparisons, the t test or chi-square test was used. Multivariate logistic regression analyses were performed to evaluate the associations between BMI and the probabilities of clinical pregnancy (CP), miscarriage and live birth (LB). Normal-weight patients were considered as the reference group.

Main results and the role of chance

Regarding confounding factors, no significant differences between BMI groups were observed.

-BMI-group comparisons showed that CP, miscarriage and LB rates significantly worsened with the increase in BMI (overweight and obesity groups). Miscarriage and LB rates also worsened with the decrease in BMI (underweight group) (Table 1).

-Compared with the normal-weight group, the overweight and obesity groups had significantly reduced rates of CP (19%/29%, respectively) and LB (27%/40%, respectively) and an increased rate of miscarriage (1.7x and 2.3x, respectively). Underweight was associated with a 49%-reduced rate of LB and a 3.0x increase in the rate of miscarriage (Table 2).

Limitations, reasons for caution

Differences in sample size between BMI groups may have influenced the results. In clinical outcomes, only fresh transfers were considered (not cumulative data). Population characteristics should be considered when interpreting the results.

Wider implications of the findings

The study suggests that higher BMI (overweight and obesity) and lower BMI (underweight) in women have a detrimental effect on ART outcomes, especially regarding the evolution of pregnancies. Problems associated with abnormal BMI should be discussed when advising couples interested in fertility treatment.

Trial registration number

Not applicable.

Digestibility prediction of cooked plantain flour as a function of water content and temperature

The effect of temperature (T=55-120°C) and water content (X1=1.4-2.0 kg kg(-1) dry basis) on the gelatinization and digestibility of plantain flour (Dominico Harton genotype) were investigated. The degree of plantain starch gelatinization (α) was measured by DSC and modelled as a function of T and X1, using the Weibull model. Rapidly digestible starch (RDS) and resistant starch (RS) fractions were evaluated for different α values. An appropriate dimensionless variable was introduced to the analyzed and modelled RDS and RS as a function of α. Starch gelatinization begins at a temperature above 59.6 ± 0.5°C and α is strongly dependent on T in non-limiting water conditions. The combined effects of T and X1 on the RDS and RS can be explained by α. We demonstrate that various heat treatments and water contents lead to the same α, with the same RDS and RS values.

Diffusion of Fibroblast Growth Factor from a Plaster of Paris Carrier

Fibroblast growth factor (FGF) is a polypeptide found in two forms: basic and acidic. The basic form is produced by many more types of cells than the acidic form, although both bind to the same receptor. These proteins act on a variety of mesodermally and ectodermally derived cells, including chondrocytes, glial cells, myoblasts, endothelial cells, cornea and lens epithelia, adrenal cortical cells, ovarian granulosa cells, periosteal fibroblasts, and osteoblasts. Basic FGF was chosen for the present study for a variety of reasons. First, it has significant cross-species homology, with 98.7% correlation between human and both bovine and avian FGF. Less conservation has been observed in the acidic form. In addition, the basic form has been shown to be 30- to 100-fold more potent, depending on the target tissue.

Interactions between MC3T3-E1 cells and textured Ti6Al4V surfaces

This paper presents the results of an experimental study of the interactions between MC3T3-E1 (mouse calvarian) cells and textured Ti6Al4V surfaces, including surfaces produced by laser microgrooving; blasting with alumina particles; and polishing. The multiscale interactions between MC3T3-E1 cells and these textured surfaces are studied using a combination of optical scanning transmission electron microscopy and atomic force microscopy. The potential cytotoxic effects of microchemistry on cell-surface interactions also are considered in studies of cell spreading and orientation over 9-day periods. These studies show that cells on microgrooved Ti6Al4V geometries that are 8 or 12 microm deep undergo contact guidance and limited cell spreading. Similar contact guidance is observed on the surfaces of diamond-polished surfaces on which nanoscale grooves are formed due to the scratching that occurs during polishing. In contrast, random cell orientations are observed on alumina-blasted Ti6Al4V surfaces. The possible effects of surface topography are discussed for scar-tissue formation and improved cell-surface integration.

A new ultrasensitive assay for quantitation of HIV-1 RNA in plasma

Nucleic acid-based diagnostic assays for the quantitation of plasma HIV-1 RNA levels are used to monitor disease progression and the response of patients to antiretroviral drug therapy. The LCx HIV RNA Quantitative Assay (Abbott Laboratories, North Chicago, IL) is an assay for the quantitation of HIV type 1 RNA in plasma that uses competitive reverse transcription PCR (RT-PCR) followed by Microparticle Enzyme Immunoassay, and includes an internal control for inhibition and RNA recovery, that is taken through the entire sample preparation procedure. The performance of the assay was assessed for 1 and 0.2 ml sample volumes. For a 1 ml sample volume, the lower limit of detection was found to be 50 copies/ml with a linear range from 50 to 1 million copies/ml. For a 0.2 ml sample volume, the lower limit of detection was found to be 178 copies/ml with a linear range from 178 to 5 million copies/ml. The assay is able to detect and quantitate HIV subtypes A-G and group O. LCx HIV RNA assay quantitation results are highly correlated to the standard and ultrasensitive Amplicor HIV-1 Monitor assay (Roche Molecular Systems) quantitation results. Assay performance is consistent with the use of this test for routine quantitation of HIV-1 RNA in plasma.

Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis

Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally.

Lack of neurotoxic effect of diethylpropion in crack-cocaine abusers

Dopamine agonists have been used with some success in treating cocaine addiction. However, both cocaine and psychostimulants have been reported to produce neurotoxic effects. We evaluated the effect of the stimulant diethylpropion on cognitive performance in a double-blind, placebo-controlled trial. Forty-six abstinent crack-cocaine users received either placebo, 25-mg, 50-mg, or 75-mg doses of diethylpropion. Patients were tested at baseline and again after 9-14 days of medication. There were no differences between placebo and medication groups on any test, indicating that, within the time frame studied, diethylpropion does not produce neurotoxic effects that can be detected with standardized neuropsychological tests.

Tricalcium phosphate and osteogenin: a bioactive onlay bone graft substitute

The disadvantages of autogenous bone grafts has prompted a search for a dependable onlay bone graft substitute. A combination of tricalcium phosphate, a resorbable ceramic, and osteogenin, an osteoinductive protein, was evaluated as an onlay bone graft substitute in a rabbit calvarial model. Twenty-eight tricalcium phosphate implants (15 mm diameter x 5 mm; pore size, 100-200 microns) were divided into experimental and control groups and placed on the frontal bone of 14 adult New Zealand White rabbits. In the experimental animals, 185 micrograms of osteogenin was added to each implant. In the control animals, the implants were placed untreated. Implants were harvested at intervals of 1, 3, and 6 months, and evaluated using hematoxylin and eosin histology, microradiography, and histomorphometric scanning electron microscope backscatter image analysis. At 1 month there was minimal bone ingrowth and little tricalcium phosphate resorption in both the osteogenin-treated and control implants. At 3 months, both the osteogenin-treated and control implants showed a modest increase in bone ingrowth (8.85 percent versus 5.87 percent) and decrease in tricalcium phosphate (32.86 percent versus 37.08 percent). At 6 months, however, the osteogenin-treated implants showed a statistically significant increase in bone ingrowth (22.33 percent versus 6.96 percent; p = 0.000) and decrease in tricalcium phosphate (27.25 percent versus 37.80 percent; p = 0.004) compared with the control implants. The bone within the control implants was mostly woven at 6 months, whereas the osteogenin-treated implants contained predominantly mature lamellar bone with well-differentiated marrow. All implants maintained their original volume at each time interval studied. The tricalcium phosphate/osteogenin composite, having the advantage of maintaining its volume and being replaced by new bone as the tricalcium phosphate resorbs, may be applicable clinically as an onlay bone graft substitute.

Phosphatidylazidothymidine and phosphatidyl-ddC: assessment of uptake in mouse lymphoid tissues and antiviral activities in human immunodeficiency virus-infected cells and in Rauscher leukemia virus-infected mice

During the early stages of human immunodeficiency virus (HIV) infection, although symptoms are absent and viral replication in peripheral blood mononuclear cells is low, substantial levels of HIV replication can be documented in lymphoid tissue [G. Pantaleo, C. Graziosi, J.F. Demarest, L. Butini, M. Montroni, C.H. Fox, J.M. Orenstein, D.P. Kotler, and A.S. Fauci, Nature (London) 362:355-358, 1993, and J. Embretsen, M. Zupancic, J.L. Ribas, A. Burke, P. Racz, K. Tenner-Tacz, and A.T. Haase, Nature (London) 362:359-362, 1993]. This observation suggests that earlier treatment of HIV infection may be indicated and that strategies for enhancing drug targeting to the lymphoid tissue reservoris of HIV infection may be beneficial. To address this issue, we synthesized dioleoylphosphatidyl-ddC (DOP-ddC) and dipalmitoylphosphatidyl-3'-azido-3'-deoxythymidine (DPP-AZT), phospholipid prodrugs which form lipid bilayers and which are readily incorporated into liposomes. The anti-HIV activity of DOP-ddC was similar to that of ddC in HIV type 1-infected HT4-6C cells, but DPP-AZT was considerably less active than AZT in HT4-6C cells. Liposomes containing DOP-[3H]ddC or DPP-[3H]AZT administered intraperitoneally to mice produced greater levels of total radioactivity over time in plasma, spleen, and lymphoid tissue relative to the results with [3H]ddC and [3H]AZT, respectively. DPP-AZT administered intraperitoneally in liposomes as a single daily dose to mice infected with Rauscher leukemia virus prevented increased spleen weight and reverse transcriptase levels in serum with a dose-response roughly comparable to that of AZT given continuously in the drinking water. DOP-ddC, DPP-AZT, and lipid conjugates of other antiretroviral nucleosides may provide higher levels of drug over time in plasma and in lymph nodes and spleen, important reservoirs of HIV infection, and may represent an interesting alternative approach to antiviral nucleoside treatment of AIDS.

Comparison of bovine collagen xenografts to autografts in the rabbit

The use of bovine tendon as a xenograft material in humans is attractive because of its ready availability and favorable mechanical characteristics. Previous research has shown that the fibroblasts and some extracellular proteoglycans and glycoproteins, not the collagen matrix itself, in bovine tendon are primarily responsible for its antigenicity. Various attempts have been made to decrease the antigenicity of these grafts. A chloroform/methanol (CM) extraction procedure has been developed that selectively removes the fibroblasts from bovine tendon without destroying the collagen matrix. The mechanical, immunologic, and local host tissue responses to these grafts were compared to autografts and to untreated and glutaraldehyde-treated bovine tendon xenografts. The humoral immune response to a purified bovine Type I collagen product was also studied. The central two-thirds of a rabbit Achilles tendon were replaced with a reversed autograft or an experimental graft. Histologic examination of one- and two- week specimens showed an acute inflammatory response to all grafts. Untreated grafts stimulated a severe inflammatory response and were almost completely resorbed by two weeks. Glutaraldehyde-treated grafts were encapsulated. Cellular repopulation was minimal and inflammatory response was more persistent than in the autograft and CM groups. Inflammatory response to CM-treated grafts was similar to that of autografts. The CM grafts repopulated rapidly with host cells. The mechanical strength of CM grafts was equal to autograft controls at 12 weeks. The mechanical strength of untreated and glutaraldehyde-treated grafts was significantly lower. Measurement of the humoral immune response to these grafts was conducted in an independent group of animals using an enzyme-linked immunosorbent assay. A significant antibody response to untreated, glutaraldehyde-fixed, and CM-treated grafts was detected at 30 days. Antibody titers to glutaraldehyde-fixed and untreated grafts remained elevated at 60 and 90 days. In the CM group, antibody titers decreased to the level of autograft controls by 90 days. No significant antibody response was detected toward purified bovine Type I collagen.

Influence of magnesium sulfate-induced hypermagnesemia on the anion gap: role of hypersulfatemia

Although hypermagnesemia purportedly lowers the anion gap (AG), we have shown previously that increases in the serum concentration of the unmeasured cation (UC) Mg due to therapeutic infusion of MgSO4 are not associated with AG reduction. To assess our hypothesis that increases in serum SO4 (unmeasured anion, UA) offset the effect of elevated serum Mg on the AG, we prospectively studied 11 patients receiving MgSO4 intravenously for toxemia of pregnancy. After 6 h of MgSO4 infusion, serum Mg increased by 2.1 +/- 0.2 (SE) mEq/l (p less than 0.001) without a significant decrease in the AG. Concomitantly, serum SO4 increased by 1.4 +/- 0.2 mEq/l. Comparison of the renal handling of SO4 versus Mg showed a higher fractional excretion of the former, probably accounting in part for the smaller increment of serum SO4 than of Mg. Comparison of the change in serum SO4 minus that of Mg indicated that, on the average, 70% of the observed 1.0 +/- 0.7 mEq/l reduction in AG was accounted for by the observed changes in the two pertinent unmeasured ions. A small decrement in serum Ca probably was a quantitatively minor factor tending to obviate a greater decrease in AG. We conclude that hypersulfatemia attenuates the reduction in AG that would otherwise accompany MgSO4-induced hypermagnesemia.

[A comparison of cyclists' time records according to altitude and materials used]

The purpose of this study was to re-assess the energy cost of track cycling in order (a) to compare the one-hour world records at sea-level and altitude with classical bicycles or with modern bicycles including aerodynamic components, and (b) to estimate the optimal altitude to set a new one-hour world record. Energy cost of track cycling with a classical or aerodynamic bicycle was estimated according to the equation developed by di Prampero et al. (1979) using data from Davies (1980) for the rolling resistance coefficient and from Gross et al. (1983) for the aerodynamic resistance coefficient for each type of bicycle. When compared to the classical track-bicycle, and to the bicycle studied by di Prampero et al. (1979), the aerodynamic track-bicycle reduces the resistance coefficient by 11.7 and 16.9% respectively. According to these estimations the cyclists sustain 87-95% of maximal aerobic power over one hour, which is a likely value for a 60 min exercise period for top-level athletes. When the reduction of air density and of maximal aerobic power with altitude are taken into account, equivalences between performances achieved at different altitudes and with the two types of track-bicycles, can be computed. The best overall performance appears to be the current one-hour record at sea-level using an aerodynamic bicycle (Moser: 50.644 km.h-1). This performance is equivalent to 53.5 km.h-1 in Mexico City (2230 m), 54.4 km.h-1 in La Paz (3417 m) and 54.5 km.h-1 at 3843 m (472 mmHg), which would be the optimal altitude to set the record.

Pseudobacteremia due to Pseudomonas fluorescens

Pseudomonas fluorescens was recovered from 62 of 22,270 (0.26%) blood cultures, from 57 patients, over a 22-month period at a pediatric hospital. No illness was attributable to the blood culture isolate. A case-control study identified a significant correlation between the recovery of P. fluorescens in blood culture and concomitant coagulation studies (p less than 0.0001). In all cases blood for coagulation studies had been obtained at the same time as the blood culture. A review of venipuncture technique revealed that occasionally the coagulation study tubes (containing 3.8% sodium citrate) were being inoculated before blood culture bottles. P. fluorescens was subsequently isolated from coagulation tubes and from sodium citrate solutions prepared and dispensed in the hospital for use in coagulation studies. In vitro studies confirmed that sodium citrate solutions supported the growth of P. fluorescens, with preferential growth at 25 degrees C and 4 degrees C. This is the first description of P. fluorescens as a cause of pseudobacteremia. Pseudobacteremia was attributed to cross-contamination of blood cultures following inoculation of contaminated citrated collection tubes.

Prolonged fever associated with primary hyperparathyroidism

A 36-year-old woman presented with hypercalcemia, hypercalciuria, elevated serum parathyroid hormone levels and prolonged fever. Surgical removal of the hyperplastic and adenomatous parathyroid glands led to reversal of the biochemical abnormalities as well as return of her temperature to normal.

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.

VO2max of cyclists from treadmill, bicycle ergometer and velodrome tests

The purpose of this study was to measure the VO2max of trained cyclists on the treadmill (means +/- SD = 54.7 +/- 6.3 ml kg-1 min-1), while riding a bicycle on a velodrome track at 100 rpm (53.7 +/- 7.8) and on the bicycle ergometer at 60 rpm (62.4 +/- 8.1): VO2max beeing the highest in the latter case (p less than 0.05). The highest maximal HR, 188 +/- 6 beats min-1, was observed during the treadmill test, while estimates of 184 +/- 6 and 179 +/- 7 were obtained for the velodrome and the bicycle ergometer tests, respectively. No significant differences were observed in the blood lactate concentrations (treadmill: 10.35 +/- 4.01 bicycle ergometer: 10.25 +/- 2.29 velodrome: 10.95 +/- 1.51 mmol L-1. In conclusion, bicycle ergometer tests might not be specific enough to evaluate the ability of trained cyclists to perform an endurance or aerobic task on the track. Trained cyclists, as opposed to untrained ones, appear to achieve higher VO2max on the bicycle ergometer as compared to the treadmill.

Skeletal muscle adaptation in adolescent boys: sprint and endurance training and detraining

The purpose of the present study was to investigate the effects of 3-month sprint and endurance training programs on the vastus lateralis muscle fiber area and the activities of glycolytic (phosphofructokinase; PFK) and oxidative (succinate dehydrogenase; SDH) enzymes of adolescent boys. Enzyme activities were also determined after a subsequent 6-month detraining period. Endurance training resulted in significant increases in VO2max (58.4 to 64.3 ml . min-1 . kg-1), in ST and FTa fiber area (6.0 to 7.3 and 8.0 to 10.4 microns 2 x 10(3), respectively), and in SDH activity (6.4 to 9.1 IU). After detraining VO2max and SDH activity returned to pretraining levels. Sprint training resulted in a significant increase only in PFK activity (28.1 to 33.9 IU), which was also abolished in the detraining period. These data demonstrate that in adolescent boys skeletal muscle enzyme changes are specific to the mode of training and that they are similar in direction but different in magnitude to those found in adults.