Search PubMed⌕ Search

Biomedical subjects

H Nathan

Publications and source records attributed to H Nathan.

At least 19 recordsLinked to original sources
PubMed1999

Circuits with surface modifying additive alter the haemodynamic response to cardiopulmonary bypass.

OBJECTIVE: Blood contact with synthetic surfaces during cardiopulmonary bypass (CPB), inevitably results in the activation of a variety of interrelated pathways of inflammation and coagulation that may contribute to postoperative complications in cardiac surgery patients. The objective of this trial was to evaluate clinical events and complement activation related to the use of a novel biomaterial, into which a surface modifying additive had been incorporated into the polymer used to prepare the bypass circuit. METHODS: A prospective, double-blind trial was carried out with 34 patients randomized to surgery, with either a standard circuit or a circuit treated ('tip to tip') with the surface modifying additive. Variables recorded included perioperative haemodynamics, volume replacement, alpha-agonist and inotrope use. Terminal complement complex (SC5b-9) was measured using an ELISA. RESULTS: Upon initiation of bypass, there was a decrease in mean arterial pressure (MAP) in the control group, not seen in the test group (P = 0.0005, ANOVA). There was a decrease in the total volume of replacement fluid given intraoperatively in the test group as compared with the control group (total plus prime; control 5.3 +/- 1.2 L, test 4.4 +/- 1.9 L, P = 0.03, Mann-Whitney test). There was a trend to decreased need for inotrope infusion in the test group after CPB (test 1/17, control 6/17, Fisher exact test; P = 0.085). No difference was seen in the generation of terminal complement complex between the groups either during or after CPB. CONCLUSIONS: The decrease in blood pressure in the control group, upon the initiation of CPB, did not occur in patients undergoing CPB with the circuit prepared with the surface modifying additive. The decrease in blood pressure was likely associated with the increase in total administered fluids intraoperatively (approximately 1 l/patient) and perhaps the trend towards higher use of inotropes in the control patients as opposed to the test patients. These haemodynamic changes did not appear to be related to complement activation early in CPB.

Cardiac Output↗
PubMed1999

Validation of a novel luminal flow velocimeter with video fluoroscopy and manometry in the human esophagus.

There is currently no ideal method for concurrently assessing intraluminal pressures and flows in humans with high temporal resolution. We have developed and assessed the performance of a novel fiber-optic laser-Doppler velocimeter, mounted in a multichannel manometric assembly. Velocimeter recordings were compared with concurrent fluoroscopy and manometry following 50 barium swallows in healthy subjects. During these swallows, the velocimeter sensor was situated in either the proximal (24 swallows) or the distal (26 swallows) esophagus. It signaled intraluminal flow following 46 of 50 swallows. A greater mean number of deflections were recorded in the distal compared with the proximal esophagus (4. 3 vs. 2.4, P = 0.001). The maximal flow velocity recorded did not differ between the proximal and distal esophagus (76.7 vs. 73.8 mm/s). No velocimeter signals commenced after fluoroscopic lumen occlusion. The velocimeter signals were closely temporally related to fluoroscopic barium flow. Upward catheter movement on swallowing sometimes appeared to cause a velocimeter signal. Manometrically "normal" swallows were no different from "abnormal" swallows in the number and velocity of deflections recorded by the velocimeter. This novel instrument measures intraluminal flow velocity and pressures concurrently, thus enabling direct study of pressure-flow relationships. Flow patterns differed between the proximal and distal esophagus.

Adult↗
PubMed1998

Requesting organ donation: an interview study of donor and nondonor families.

BACKGROUND: Approximately half of the families asked to consider donation of a relative's organs decline to give consent. Understanding the difference between stated public support of organ donation and actual behavior is key to decreasing the shortage of donor organs. OBJECTIVES: To gain insight into the experiences of potential donor families and to define features of the donation-request process and other factors that are associated with consent for organ donation. METHODS: A structured telephone interview was conducted with the immediate next of kin of 164 medically suitable potential organ donors. Interviews 30 to 60 minutes long were held with members of both donor and nondonor families 4 to 6 months after the death of the study participant's relative. RESULTS: Several factors were associated with consent for organ donation: characteristics of the patient and the patient's family, beliefs and attitudes about organ donation and transplantation, whether the family knew the deceased's wishes about donation, the family's satisfaction with the hospital care that their relative received, specific aspects of the donation-request process, and the family's understanding of brain death. CONCLUSIONS: Organ donation rates could be increased by enhancing the quality of hospital care and ensuring that the request for donation is handled in a way that meets the families' informational and emotional needs.

Adolescent↗
PubMed1997

Explaining brain death: a critical feature of the donation process.

To examine how a family's understanding of brain death may affect the decision to donate, an interview study was conducted with the immediate next of kin of 164 medically suitable organ donor candidates. Telephone interviews were conducted with members of both donor and nondonor families 4 to 6 months after the relative's death. Only 61% of the donor and 53% of the nondonor respondents said they had received an explanation of brain death. Few respondents reported that the hospital or organ procurement organization staff used visual aids to clarify or reinforce the information they were given. Next of kin who decided against donation had far less understanding of brain death than did those who decided in favor of it. Before making an organ donation request, healthcare providers must inquire about and address common misunderstandings people have about brain death. Healthcare teams should develop and be trained on a clear protocol for communicating with the families of patients who may be potential organ donors.

Adolescent↗
PubMed1996

Right ventricular blood flow during left ventricular support in an experimental porcine model.

BACKGROUND: Right ventricular blood flow may be adversely affected during left ventricular assist device (LVAD) use leading to right ventricular (RV) ischemia and RV dysfunction. This study characterized normal RV blood flow responses to LVAD operation. METHODS: Seven Yorkshire pigs weighing 74.4 +/- 3.4 kg underwent right coronary artery blood flow measurements with an ultrasonic flow probe and injection of radiolabeled microspheres. A Thoratec LVAD was used in either synchronous or asynchronous modes and RV loading was increased using a pulmonary artery snare. RESULTS: The RV blood flow was compared between three regions that differed in proximity to the right coronary artery: proximal segment, mid-RV, and distal. The right ventricular distal flow was 0.93 +/- 0.07 mL x min-1 x g-1 compared with 0.74 +/- 0.06 mL x min-1 x g-1 at right ventricular proximal flow during control measurements (p = 0.0001). This difference was maintained during LVAD operation in either synchronous or asynchronous modes and also during pulmonary artery constriction. CONCLUSIONS: Global RV flow is not adversely affected by LVAD use. A flow gradient occurs along the right coronary artery with the distal vascular bed having relatively less reserve, which may be more susceptible to ischemia in patients with preexisting coronary disease or RV distention during LVAD use.

Animals↗
PubMed1994

Levels of prostaglandin E2 and leukotriene B4 in tears of vernal conjunctivitis patients during a therapeutic trial with indomethacin.

A therapeutic trial of 1% indomethacin (Indoptic) eye drops was carried out in 21 children. Looking for possible mediators of inflammation in vernal conjunctivitis, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4 levels in the tears of 9 patients were measured and the effect of the treatment on them examined. A control group of 10 unaffected children was added. Out of 42 eyes in which indomethacin treatment was instilled, only 17 remained in treatment through a 6-week follow-up period. In a few of them a moderate improvement was obtained. The mean level of PGE2 in the patients before treatment was found to be slightly lower than that in the control group, and it dropped even lower during treatment. The average LTB4 level found in patients before treatment was significantly higher than the control group; it decreased somewhat following treatment, but not significantly. This is the first report of elevated LTB4 levels in vernal conjunctivitis, previously not recorded in the literature, it points to the possible role of LTB4 in the pathogenesis of the disease. A constant relationship was observed between low PGE2 levels and high LTB4 content in the patients' tears during highly inflamed states of the eye. We conclude that: (a) indomethacin did not prove to be a highly effective topical treatment for vernal conjunctivitis; (b) PGE2 does not seem to be a dominant mediator of inflammation in this disease; and (c) LTB4, on the other hand, apparently has a role in the mechanism of inflammation of the disease, thus raising hopes for future addition to therapy.

Adolescent↗
PubMed1993

Combined team effort in liver procurement and transplantation: 5-year experience of one organ procurement organization.

Combined team effort in liver procurement and transplantation has proven to be very advantageous as compared to same team effort in our experience. The incidence of primary nonfunction was almost identical between the two groups. We recommend that a combined team effort be used in liver transplantation to conserve the resources and ensure the safety of the transplant team. The practice of only a single local recovery team for all abdominal organ procurement should be encouraged.

Delaware↗
PubMed1993

Cadaveric renal transplant in the highly sensitized African-American patient.

A statistically significant difference was discovered when comparing the 1-year graft survival of CAUC and AA. The difference was due in part to nine AA failures that occurred within the first week posttransplant (Fig 3). Using a multivariant analysis both the AA and CAUC were found to be normally distributed in regard to CIT, HLA mismatch, transplant number, and PRA. If these traditional variables thought to have relevance on graft survival in cadaveric renal transplantation are ruled out as contributing factors other avenues must be explored. If credence is given to the theory that the difference in function between AA and CAUC is due to the difference in the number of transplants that failed within the first week then factors such as immunosuppressive therapy and noncompliance can also be ruled out. One possible area of explanation may lie in the area of specificity to HLA antibody. It is possible that these recipients received transplants from a donor to which they were sensitized. A closer analysis of donor and recipient HLA typing as well as the recipient's transfusion and transplant history is recommended. Despite the fact that all transplants occurred in the presence of negative preliminary and final XM's using American Society for Histocompatibility and Immunogenetics (ASHI) certified techniques (Table 2), transplant centers may wish to consider using a more sensitive XM technique such as flow cytometry for these patients. We hope that these recommendations will enable transplant centers to continue their commitment to transplanting the highly sensitized recipient.

Black or African American↗
PubMed1993

Organ donation and referrals among African-Americans.

Solid organ referrals for AA have been growing since 1989. One third of AA referrals are in the 16 to 30 year age group with the majority of these males suffering traumatic injury. AA donors have increased from 11 in 1989 to 32 in 1992. This is in spite of AA and minority consent rates that are 20% to 30% below that of the CAUC group. This gap represents a vital opportunity for improvement. Increased education to minority groups with a message that considers the ethnic and cultural diversity of the minority community coupled with an increase in the number of minority transplant coordinators should help to increase the number of AA referrals and donors.

Adolescent↗
PubMed1991

Recipient race does not influence waiting time for a cadaveric renal transplant--one organ procurement organization's experience.

There was no statistical significance to the differences in waiting time for cadaveric renal transplant by race. Whether for first transplant or second or greater, any differences in waiting time could not be accounted for by the recipient's race. CAUC made up 58% of the waiting list, 65% of the recipients, and 87% of the donors. The corresponding numbers for AA are: 38%, 29%, and 10%, respectively. More regional serum-sharing trays may be needed in order to expose recipients with high PRA to as many donors as possible in order to lessen their waiting time. It should be noted that fewer HLA mismatches occurred when donor and recipient race were identical. In light of this data, more study is needed to determine the relationship between donor and recipient race, corresponding HLA mismatches, and graft survival. If antigen-matching is found to increase graft survival, then an increase in minority donations will be required. Until that time, under the current allocation system and with the predominance of Caucasian donors, it is likely that Afro-Americans will continue to receive kidneys that have more HLA antigen mismatches than if Afro-Americans donated in numbers equivalent to their percentage of the waiting list.

Adult↗
PubMed1990

Impact of a required request law on vital organ procurement.

"Mandatory" or required request for donation of the organs of patients dying in hospitals has been promulgated as a means of increasing the rate of organ harvest and alleviating the critical shortage of transplantable organs. Although the federal and many state governments have passed legislation to make such requests compulsory, the efficacy of this approach has not been demonstrated. Examination of the experience at our trauma center and in this region, before and after the enactment of a "strong" required request law by the State of New Jersey, did not reveal a statistically significant change in organ procurement. We conclude that such laws are unlikely to achieve the desired result in the absence of fundamental changes in the attitudes of the public and treating physicians.

Age Factors↗
PubMed1989

Failure to predict intraoperative myocardial ischaemia in patients with coronary artery disease.

Patients with severe coronary artery disease were studied to determine if the preoperative assessment or intraoperative haemodynamic monitoring could predict the occurrence of myocardial ischaemia. Thirty-eight patients undergoing coronary artery surgery who had normal electrocardiograms before induction of anaesthesia were included. Leads II and CS5 were recorded on a Holter monitor and radial arterial and pulmonary artery catheters were used to measure haemodynamic variables. Eight patients developed ST-segment changes greater than or equal to 0.1 mV before sternotomy. Preoperative factors could not be used to predict which patients would develop ST-segment changes. In all 38 patients haemodynamic determinants of myocardial oxygen supply and demand remained within an optimal range despite evidence of ischaemia in eight. This syndrome of ECG changes in the absence of tachycardia and hypertension resembles the syndrome of silent ischaemia documented in awake patients. Our findings suggest that myocardial ischaemia may be caused by decreases in coronary blood flow not associated with changes in haemodynamic variables.

Adult↗
PubMed1989

The inguinal region: anatomic differences in men and women with reference to hernia formation.

Fifty inguinal regions were dissected in anatomic human adult specimens, of which 26 were males and 24 females. The comparison of anatomic variations in both sexes showed that the distance between the public tubercle and the internal ring was larger, and the rectus muscle significantly wider in females. The diameter of the internal ring was larger in males, however, with significant variability. No differences were found regarding the presence or absence of the conjoint tendon. The anatomic variations may explain the sex differences in hernia formation.

Anatomy↗
PubMed1989

Germ cell tumors of the testicle or 'orchidomata'.

An unusual case of a double testicular tumor, with different histology and the same marker chromosome, led to a search of the literature for cases of testicular tumors that were double, bilateral, or familial. The literature on abnormal chromosomes in tumors of the testis is also reviewed. After a discussion of the facts, it is suggested that most of the histological variants of germ cell tumors of the testicle are so closely related that they could be grouped together under the title of 'orchidomata'.

Chromosome Aberrations↗