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Biomedical subjects

B Cohen

Publications and source records attributed to B Cohen.

At least 379 records · Page 21Linked to original sources
PubMed1984

Surrogate mothers: whose baby is it?

Advances in medical technology offer infertile couples who wish to raise children alternatives to adoption. The increasing number of surrogate mother contracts creates a myriad of legal issues surrounding the rights of the natural mother, the natural father and the child that is produced. In this Article, the Author discusses the legal issues and rights of the parties under the Constitution, the surrogate contract and family law principles. The Author proposes that courts should consider a surrogate contract as a revocable prebirth agreement which allows the natural mother to keep the child if she chooses. In addition, the Author advocates an interpretation of the statutes forbidding baby selling that would prohibit surrogate contracts in which the mother is paid a fee for the child.

Child Advocacy↗
PubMed1983

Diagnosis of human lymphoma with monoclonal antileukocyte antibodies.

Two monoclonal antibodies have been produced that react with antigens present on human white cells. These reagents differ from other monoclonal antibodies of similar specificity in that the antigens they recognize are resistant to conventional tissue-fixation and embedding procedures. These reagents can therefore be used in immunocytochemical staining of paraffin-embedded tissue sections. We assessed the practical usefulness of this technique in the histopathological diagnosis of human lymphoid neoplasms by staining a wide range of routine surgical biopsy specimens of normal and neoplastic tissue (gathered from five institutions), using an indirect immunoperoxidase technique. In all 40 cases of non-Hodgkin's lymphoma, positive labeling of neoplastic cells was obtained with one or both antibodies. In contrast, no staining of neoplastic cells was observed in 60 samples of nonlymphoid neoplasms. We conclude that many of the difficulties encountered by histopathologists in distinguishing between lymphoid and nonlymphoid neoplasms may be overcome by immunohistologic labeling with monoclonal antibodies such as the ones we have studied.

Animals↗
PubMed1983

Role of the otolith organs in generation of horizontal nystagmus: effects of selective labyrinthine lesions.

Selective labyrinthine lesions were made to study the origin of excitation in the labyrinth during off-vertical axis rotation. Plugging the semicircular canals abolishes the response to rotation about a vertical axis, but optokinetic after-nystagmus (OKAN) and the sustained horizontal nystagmus induced by off-vertical axis rotation (OVAR) are maintained. After cutting the nerves of the lateral semicircular canals, neither horizontal OKAN nor the continuous horizontal nystagmus associated with off-axis rotation can be induced, although vertical OKN, OKAN and vestibular nystagmus are intact. This supports the theory that labyrinthine activity responsible for the nystagmus induced by OVAR arises in the otolith organs and couples to the oculomotor system through the velocity storage mechanism.

Animals↗
PubMed1983

Nystagmus generated by sinusoidal pitch while rotating.

Sinusoidal pitch while rotating about a vertical axis in darkness causes continuous horizontal compensatory nystagmus in the monkey which persists for the duration of stimulation. The steady-state velocity sums with post-rotatory nystagmus to reduce or cancel it, suggesting involvement of the velocity storage mechanism. Analysis of the labyrinthine excitation during pitch while rotating suggests that the vertical canals play a predominant role in generating the response. Effects of selective labyrinthine lesions are in agreement with this hypothesis. Plugging the lateral canals, leaving the vertical canals intact, blocked the initial rapid response at the onset of rotation, but did not interrupt the continuous nystagmus induced by pitch while rotating. On the other hand, plugging the vertical canals abolished the response. If the lateral canal nerves were cut so that the velocity storage mechanism was inactivated, the continuous response to pitch while rotating also disappeared. The dominant labyrinth activation responsible for the nystagmus during pitching while rotating appears to arise in the vertical semicircular canals and to couple to the oculomotor system through the velocity storage mechanism.

Animals↗
PubMed1983

Excellent outcome after transplantation of renal allografts from HLA-DRw6-positive donors even in HLA-DR mismatches.

The effect of the presence or absence in the donor of HLA-DRw6 on the survival of renal allografts was studied in 759 HLA-DRw6-negative recipients. The definition of HLA-DRw6 was consistent throughout the study period. 578 patients received an allograft with one HLA-DR mismatch and 181 an allograft with two HLA-DR mismatches. Allograft survival at 1 year was significantly better when the donors were HLA-DRw6-positive than when they were HLA-DRw6-negative, for both one-DR-mismatched (86% vs 65%) and two-DR-mismatched (85% vs 59%) allografts.

Cytotoxicity Tests, Immunologic↗
PubMed1983

HLA-DRw6 and renal allograft rejection.

HLA-DRw6-positive patients are "high responders" to certain renal allograft antigens. A study was therefore conducted of the outcome of 247 first renal allografts in 74 DRw6-positive and 173 DRw6-negative recipients. The effectiveness of matching for HLA-DR determinants in both groups was also analysed. The one-year graft survival in DRw6-positive patients was 59% as compared with 75% in DRw6-negative recipients (p = 0.012). A striking difference between the two groups was that HLA-DR matching significantly improved renal allograft survival only in the DRw6-positive patients. In those patients the one-year survival of HLA-DR-identical grafts was 95% as compared with only 38% for 2-DR mismatched grafts (p = 0.009). In DRw6-negative patients only a slight beneficial effect of HLA-DR matching was observed (83% versus 72% at one year for the 0-DR and 2-DR mismatched grafts, respectively) (p greater than 0.05). These findings are clear evidence that DRw6-positive patients (about a quarter of the patients on the waiting list of Eurotransplant) should be given HLA-DR-identical kidney transplants only.

Graft Rejection↗
PubMed1983

Preservation of cadaveric kidneys. Cold storage or machine perfusion?

Transplantation results after kidney preservation by means of cold storage and machine perfusion were analyzed. Graft survival and function of 75 machine-perfused kidneys were the same as those of 2,686 kidneys preserved by cold storage. Cold storage, a relatively simple, safe, and inexpensive procedure, was preferred for the preservation of kidneys that had not been subjected to prolonged periods of warm ischemia. Machine perfusion could be used for kidneys damaged by ischemia, although its advantage over cold storage in these circumstances was not firmly established.

Cadaver↗
PubMed1983

Flocculectomy and unit activity in the vestibular nuclei during visual-vestibular interactions.

Activity of neurons in the vestibular nuclei of alert monkeys was recorded extracellularly after total unilateral and bilateral flocculectomy and partial paraflocculectomy. Type 1 horizontal cells that were encountered after flocculectomy responded to visual and vestibular stimuli and to conflict stimulation, i.e., to rotation in a subject-stationary visual surround, as do vestibular neurons in the normal animal. The major difference between neurons in the normal and lesioned animals was that more time was needed to reach steady state firing levels during optokinetic stimulation at a constant velocity after operation. As shown previously (Waespe et al. 1983) the longer time course is related to increased initial retinal slip velocities that occur after flocculectomy as a result of an inability to change eye velocity rapidly in response to visual stimulation. It does not signify a change in the dynamics of neurons in the vestibular nuclei that mediate the vestibulo-ocular reflex (VOR). The similarity in modulation of horizontal Type 1 vestibular neurons in normal and flocculectomized monkeys makes it unlikely that floccular Purkinje cells suppress the horizontal VOR in the monkey during conflicting visual and vestibular stimuli by inhibiting or disfacilitating secondary or tertiary vestibular neurons. This is consistent with earlier findings that indicate that visual-oculomotor pathways responsible for ocular pursuit or for rapid changes in OKN do not go through the vestibular nuclei. Rather the point of interaction of the flocculus output with the VOR appears to be external to the vestibular nuclei. There was a close correspondence between the slow phase velocity of nystagmus and unit activity in the vestibular nuclei under a wide variety of test conditions after flocculectomy. This is consistent with the postulate that frequencies of vestibular nuclei neurons represent a summation of activity in direct vestibulo-oculomotor pathways and indirect pathways that include the velocity storage mechanism. These are the major remaining sources of activity that generate slow phases of nystagmus after the direct visual-oculomotor pathways have been partially interrupted by flocculectomy (Waespe et al. 1983). Horizontal Type 1 neurons which responded to vestibular and optokinetic stimulation with increases in frequency above 1 spike/s/degree/s were rarely encountered after flocculectomy. These cells were present on the normal side in a monkey after unilateral flocculectomy. We infer that vestibular nuclei neurons that project mossy fibers to the flocculus are inactivated or disappear as a result of surgical ablation of their axons. This could also contribute to the reduced gain of vestibular nystagmus, OKAN and off-vertical nystagmus that was observed in some of the animals after lesion.

Animals↗
PubMed1983

Role of the flocculus and paraflocculus in optokinetic nystagmus and visual-vestibular interactions: effects of lesions.

Optokinetic nystagmus (OKN), optokinetic after-nystagmus (OKAN), vestibular nystagmus and visual-vestibular interactions were studied in monkeys after surgical ablation of the flocculus and paraflocculus. After bilateral flocculectomy the initial rapid rise in slow phase eye velocity of horizontal and vertical OKN was severely attenuated, and maximum velocities fell to the preoperative saturation level of OKAN. There is generally little or no upward OKAN in the normal monkey, and upward OKN was lost after bilateral lesions. Unilateral flocculectomy affected the rapid rise in horizontal velocity to both sides. Consistent with the absence of a rapid response to steps of surround velocity, animals were unable to follow acceleration of the visual field with eye accelerations faster than about 3-5 degrees/s2. The slow rise in OKN slow phase velocity to a steady state level was prolonged after operation. However, rates of rise were approximately equal for the same initial retinal slips before and after operation. The similarity in the time course of OKN when adjusted for initial retinal slip, and in the gain, saturation level and time course of OKAN before and after flocculectomy indicates that the lesions had not significantly altered the coupling of the visual system to the velocity storage integrator or its associated time constant. When animals were rotated in a subject-stationary visual surround after flocculectomy, they could not suppress the initial jump in eye velocity at the onset of the step. Despite this, they could readily suppress the subsequent nystagmus. The time constant of decline in the conflict situations was almost as short as in the normal monkey and was in the range of the peripheral vestibular time constant. This suggests that although the animals were unable to suppress rapid changes in eye velocity due to activation of direct vestibulo-oculomotor pathways, they had retained their ability to discharge activity from the velocity storage mechanism. Consistent with this, animals had no difficulty in suppressing OKAN after flocculectomy. Visual-vestibular interactions utilizing the velocity storage mechanism were normal after flocculectomy, as was nystagmus induced by rotation about a vertical axis or about axes tilted from the vertical. Also unaffected were the discharge of nystagmus caused by tilting the head out of the plane of the response and visual suppression of nystagmus induced by off-vertical axis rotation. The flocculus does not appear to play an important role in mediating these responses. The data before and after flocculectomy were simulated by a model which is homeomorphic to that presented previously.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Regulation of intracellular chloride activity during perfusion with hypertonic solutions in the Necturus proximal tubule.

In a previous study we presented evidence that chloride transport across the basolateral membrane in Necturus proximal tubule cells occurs predominantly via exchange for both Na+ and HCO3-. In this study the regulation of intracellular chloride was further examined in the doubly-perfused kidney preparation using conventional and chloride-sensitive microelectrodes. Application of hypertonic basolateral solutions containing 80 mM raffinose stimulated an efflux of chloride such that chloride activity remained unchanged at control levels. Membrane potential did not change in these experiments. Inhibition of Cl- exit across the basolateral cell membrane by removal of either HCO3- or Na+ from the perfusion solution resulted in a significant increase in intracellular chloride activity, aiCl, when basolateral osmolarity was raised. Hypertonic basolateral solutions also produced a significant rise in aiCl in the presence of SITS. This study provides further evidence that chloride is transported across the basolateral cell membrane in exchange for both Na+ and HCO3-. Since this exchange mechanism is activated in response to hypertonic solutions, these studies suggest a functional role for this exchanger in the regulation of aiCl in the Necturus proximal tubule cell during volume changes.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1983

Postoperative catheterization and prophylactic antimicrobials in children with hypospadias.

A prospective study of 78 children who underwent 84 operations for correction of hypospadias was done. Of these, 54 had a transperineal indwelling Foley catheter for ten days after surgery and 30, a transurethral catheter. Forty-five randomly selected children received prophylactic antimicrobial therapy (sulfamethoxazole), and the remaining 39 children served as controls. Incidence of urinary tract infection was significantly higher in the control group (10 of 39) as compared with the treated group (3 of 45) in spite of the higher incidence of vesicoureteral reflux in the treated group. This suggests that prophylactic antimicrobial treatment may prevent urinary tract infection from prolonged indwelling catheterization.

Catheters, Indwelling↗
PubMed1983

Digital subtraction intravenous left ventricular angiography: comparison with conventional intraventricular angiography.

Standard contrast left ventriculography with catheter placement into the left ventricle entails risks and inconvenience. Computer-based digital subtraction techniques now permit high contrast left ventriculography after intravenous administration of contrast medium. To compare the accuracy of intravenous digital subtraction left ventriculography with film-based, standard contrast ventriculography, we assessed left ventricular function by both methods in 32 patients (8 with valvular disease, 22 with coronary disease and 2 with atypical pain). Studies in 31 of 32 patients were considered. Left ventricular ejection fraction by standard contrast ventriculography ranged from 24 to 88%. Digital subtraction angiography was performed with bolus injection of radiopaque contrast material (30 cc at 20 cc/s) into the inferior vena cava. The two methods correlated closely in end-diastolic volume (correlation coefficient [r] = 0.96, probability [p] less than 0.001), end-systolic volume (r = 0.97, p less than 0.001) and ejection fraction (r = 0.98, p less than 0.001). Segmental function was assessed visually; precise agreement existed between the two techniques in 123 (79%) of the 155 segments (p less than 0.001). It is concluded that intravenous digital angiography provides left ventricular images of sufficiently good quality to allow accurate quantitative assessment of global left ventricular function and volumes as well as determination of regional function.

Adult↗
PubMed1983

Exercise left ventriculography utilizing intravenous digital angiography.

Exercise left ventriculography has been shown to be a sensitive and specific tool for the detection of coronary artery disease. At the present time, such studies require radionuclide-base methods. Computer-based techniques recently have been shown to provide high resolution images of the left ventricle when the levophase of an intravenous injection of radiopaque contrast medium is imaged with fluoroscopy. To evaluate the possible efficacy of using "intravenous digital subtraction left ventriculograms" in exercise ventriculography, such ventriculograms were performed at rest and during maximal supine bicycle exercise in 31 patients. Studies that could be analyzed were obtained in 29 patients. In 21 patients with coronary artery disease, ejection fraction was 58% at rest and 45% with exercise (p less than 0.001 vs. rest). In contrast, in seven patients with no coronary artery disease, ejection fraction was 65% at rest and 69% with exercise (difference not significant). In a subgroup of 8 patients with "severe" coronary obstruction, the change in ejection fraction from rest to exercise was -18%, while in the remaining 13 patients with less severe disease, it was -9% (p less than 0.001). All patients with coronary artery disease manifested new or worsening segmental wall abnormality with exercise, compared with two of seven patients without coronary disease (p less than 0.01). Sixteen patients underwent rest and exercise radionuclide cineangiography in addition to digital subtraction angiography. There was a strong correlation between the two techniques for ejection fraction at rest (r = 0.78, p less than 0.001), ejection fraction and with exercise (r = 0.83, p less than 0.001) and change in ejection fraction from rest to exercise (r = 0.88, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Antibody responses to antigens of Streptococcus mutans in monkeys (Macaca fascicularis) immunized against dental caries.

Immunization of rabbits or monkeys with walls prepared from Streptococcus mutans by a procedure including extraction with SDS at room-temperature induced antibodies to three antigens (A, B and C) detectable by crossed immunoelectrophoresis. Antigens A and B have previously been characterized as proteins of molecular weight 29 000 and 190 000, respectively. Antigen C was characterized as having a molecular weight of 70 000 and was purified by immunosorbent affinity chromatography and hydrophobic interaction chromatography. Another wall protein, antigen D, of molecular weight 13 000, was extracted from walls with Triton X-100. Immunization of monkeys with walls prepared from cultures of S. mutans grown at a high (D = 0.5 h-1) or low (D = 0.05 h-1) dilution rate in a chemostat showed that only the latter induced protection against dental caries. There was a positive correlation between levels of antibody to antigens A and C and induction of protection and a negative correlation between protection and the level of antibody to antigen B. No antibody to antigen D was detected in protected monkeys and an experiment in which monkeys were immunized with pure antigen D confirmed that it does not induce protection.

Animals↗