Monoclonal antibodies directed against the EGF receptor show differential bindings of amphiregulin and EGF to the EGF receptor

Amphiregulin (AR), a new member of the EGF family of ligand, is a glycoprotein containing a 78 or 84 amino acid core polypeptide that was originally purified from the conditioned medium of the breast carcinoma cell line MCF-7 after treatment with phorbol 12-myristate 13-acetate. The aim of the present study was to determine whether, like EGF, TGF alpha, heparin binding EGF-related growth factor (HB-EGF) and betacellulin (ETC), the recombinant 78 amino acid form of mature human AR transmits its biological effects following binding to the EGF receptor (EGFR). We show that unlike EGF, TGF alpha, HB-EGF and BTC, the mature AR is not effective in blocking the binding of I-125-EGF or the iodinated anti-EGFR antibodies (mAbs) I-125-ICR62 and I-125-ICR80 to the external domain of the EGF receptor on EJ cells. Again, in contrast to other EGF ligands, AR is not effective in enhancing the binding of another anti-EGFR mAb ICR9 to the EGFR on EJ cells. Like EGF, TGF alpha and HB-EGF, AR could inhibit the growth in culture of EGFR overexpressing tumour cell lines, namely HN5, HSC-1 and MDA-MB468 cells, and again compared to other ligands AR was moderately effective at low concentration. Despite these differences, we show that like EGF, AR could induce the tyrosine phosphorylation of the 170 kDa EGF receptor on HN5 cells and that this effect could be blocked in the presence of anti-EGFR mAbs ICR62 and ICR80. Moreover, like EGF, the AR-induced growth inhibition of MDA-MB468 cells could also be reversed in the presence of anti-EGFR mAbs ICR62 and ICR80. On the basis of our results we conclude that, unlike the EGF, TGF alpha, HB-EGF and BTC, the AR-induced activation of the EGFR may involve another receptor.

Organ shortages: maximising the donor potential

Of all the problems foreseen in the pioneering days of organ transplantation, a shortage of donor organs, was not even remotely considered as a barrier to progress. Such has been the success of transplantation over the last two decades, organ shortage is now considered the major limitation. This chapter will concentrate on efforts to increase the donor potential. The development of Organ Exchange Organizations is briefly described with special emphasis on their role in organ allocation systems to avoid wastage of this precious resource, procurement transplant coordinators, the organization of organ procurement and the consent process. We look briefly at the influence of the media and end with some considerations on how to maximise the current supply of organs for transplantation.

Does the anchorage form and depth influence the pull-out strength of screws from bone cement? An experimental study

The pull-out strengths of cortical screws inserted into soft, unpolymerised Refobacin Palacos bone cement (procedure S) and into hardened polymerised cement into which a hole had been drilled and tapped (procedure P) were compared. Cortical screws 58 mm in length, outer diameter 4.5 mm and inner diameter 2.95 mm were used. Screws were inserted into cement cylinders at 5 mm incremental depths between 10 and 30 mm. At a screw depth of less than 25 mm, the screws pulled out, and at a depth of greater than 25 mm, the screws broke in both procedures. There was no statistically significant difference in pull-out strength leading to burst or break between the two procedures for screws inserted to comparable depths, but there was a statistically significant difference regarding the screwing depth regardless of the procedure of screw insertion chosen. The average material stability (sigma) of the cortical screws used was calculated to be 1191 N/mm2, and the elasticity limit was 5137 N. This study demonstrated that the material stability and not the depth of screw insertion was the limiting parameter in screw anchorage in bone cement while static testing. To avoid screw breakage due to fatigue during continuous alternate loading, the screws should not be loaded above this value.

Antinociceptive effect of nifedipine and verapamil tested on rats chronically exposed to nicotine and after its withdrawal

Antinociceptive effect of nifedipine (15 mg/kg i.p.) and verapamil (10 mg/kg s.c.) was examined in rats chronically exposed to nicotine (6 mg/kg/day via Alzet osmotic pump for 28 days) and after nicotine withdrawal. Sham operated rats served as control for testing DMSO (dimethylsulfoxide, a solvent for nifedipine), nifedipine and verapamil alone. Nociception was measured by the tail-flick technique. Nifedipine, but not verapamil, injected to control rats produced a ceiling tail-flick latency (20 sec) 30 min after the injection, lasting for 10 min. In rats exposed to chronic nicotine for 3 days, nifedipine treatment exhibited ceiling tail-flick latency within 10 min lasting for 80 min. Tested in rats exposed to nicotine for 3 weeks, nifedipine treatment produced this effect 25 min after the injection lasting for 60 min. Nicotine withdrawal abolished this effect. Verapamil did not exhibit any significant changes in tail-flick latencies. These data support our hypothesis that smoking patients treated with nifedipine could be at a potential risk in developing a high pain threshold and missing the first sign of heart attack--a chest pain.

Modulation of insulin activities by leptin

Leptin mediates its effects on food intake through the hypothalamic form of its receptor OB-R. Variants of OB-R are found in other tissues, but their function is unknown. Here, an OB-R variant was found in human hepatic cells. Exposure of these cells to leptin, at concentrations comparable with those present in obese individuals, caused attenuation of several insulin-induced activities, including tyrosine phosphorylation of the insulin receptor substrate-1 (IRS-1), association of the adapter molecule growth factor receptor-bound protein 2 with IRS-1, and down-regulation of gluconeogenesis. In contrast, leptin increased the activity of IRS-1-associated phosphatidylinositol 3-kinase. These in vitro studies raise the possibility that leptin modulates insulin activities in obese individuals.

Administration of pegylated recombinant human megakaryocyte growth and development factor to humans stimulates the production of functional platelets that show no evidence of in vivo activation

This report describes the effect of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on platelet production and platelet function in humans. Subjects with advanced solid tumors received PEG-rHuMGDF daily for up to 10 days. There was no increase in circulating platelet count at doses of 0.03 or 0.1 microgram/kg/d by day 12 of study. At doses of 0.3 and 1.0 microgram/kg/d there was a threefold median increase (maximum 10-fold) in platelet count by day 16. The platelets produced in vivo in response to PEG-rHuMGDF showed unchanged aggregation and adenosine triphosphate (ATP)-release responses in in vitro assays. Tests included aggregation and release of ATP in response to adenosine diphosphate (ADP) (10, 5, 2.5, and 1.25 mumol/L), collagen (2 micrograms/mL), thrombin-receptor agonist peptide (TRAP, 10 mumol/L) and ristocetin (1.5 mg/mL). Administration of aspirin to an individual with platelet count of 1,771 x 10(3)/L resulted in the typical aspirin-induced ablation of the normal aggregation and ATP-release response to stimulation with arachidonic acid (0.5 mg/mL), collagen, and ADP (2.5 and 1.25 mumol/L). There was no change in the expression of the platelet-surface activation marker CD62P (P-selectin) nor induction of the fibrinogen binding site on glycoprotein IIb/IIIa as reported by the monoclonal antibody, D3GP3. An elevation of reticulated platelets was evident after 3 days of treatment with PEG-rHuMGDF and preceded the increase in circulating platelet count by 5 to 8 days; this reflected the production of new platelets in response to PEG-rHuMGDF. At later time points, the mean platelet volume (MPV) decreased in a manner inversely proportional to the platelet count. Levels of plasma glycocalicin, a measure of platelet turnover, rose 3 days after the initial increase in the peripheral platelet count. The level of plasma glycocalicin was proportional to the total platelet mass, suggesting that platelets generated in response to PEG-rHuMGDF were not more actively destroyed. Thus, the administration of PEG-rHuMGDF, to humans, increased the circulating platelet count and resulted in fully functional platelets, which showed no detectable increase in reactivity nor alteration in activation status.

Efferent pathways of the nucleus of the optic tract in monkey and their role in eye movements

To clarify the role of the pretectal nucleus of the optic tract (NOT) in ocular following, we traced NOT efferents with tritiated leucine in the monkey and identified the cell groups they targeted. Strong local projections from the NOT were demonstrated to the superior colliculus and the dorsal terminal nucleus bilaterally and to the contralateral NOT. The contralateral oculomotor complex, including motoneurons (C-group) and subdivisions of the Edinger-Westphal complex, including motoneurons (C-group) and subdivisions of the Edinger-Westphal complex, also received inputs. NOT efferents terminated in all accessory optic nuclei (AON) ipsilaterally; contralateral AON projections arose from the pretectal olivary nucleus embedded in the NOT. Descending pathways contacted precerebellar nuclei: the dorsolateral and dorsomedial pontine nuclei, the nucleus reticularis tegmenti pontis, and the inferior olive. Direct projections from NOT to the ipsilateral nucleus prepositus hypoglossi (ppH) appeared to be weak, but retrograde tracer injections into rostral ppH verified this projection; furthermore, the injections demonstrated that AON efferents also enter this area. Efferents from the NOT also targeted ascending reticular networks from the pedunculopontine tegmental nucleus and the locus coeruleus. Rostrally, NOT projections included the magnocellular layers of the lateral geniculate nucleus (lgn); the pregeniculate, peripeduncular, and thalamic reticular nuclei; and the pulvinar, the zona incerta, the mesencephalic reticular formation, the intralaminar thalamic nuclei, and the hypothalamus. The NOT could generate optokinetic nystagmus through projections to the AON, the ppH, and the precerebellar nuclei. However, NOT also projects to structures controlling saccades, ocular pursuit, the near response, lgn motion sensitivity, visual attention, vigilance, and gain modification of the vestibulo-ocular reflex. Any hypothesis on the function of NOT must take into account its connectivity to all of these visuomotor structures.

Modulation of vergence by off-vertical yaw axis rotation in the monkey: normal characteristics and effects of space flight

Horizontal movements of both eyes were recorded simultaneously using scleral search coils in 2 rhesus monkeys before and after the COSMOS 2229 space-flight of 1992-1993. Another 9 monkeys were tested at comparable time intervals and served as controls. Ocular vergence, defined as the difference in horizontal position between the left and right eyes, was measured during off-vertical yaw axis rotation (OVAR) in darkness. Vergence was modulated sinusoidally as a function of head position with regard to gravity during OVAR. The amplitude of peak-to-peak modulation increased with increments in tilt of the angle of the rotational axis (OVAR tilt angle) that ranged from 15 degrees to 90 degrees. Of the 11 monkeys tested, 1 had no measurable modulation in vergence. In the other 10, the mean amplitude of the peak to peak modulation was 5.5 degrees +/- 1.3 degrees at 90 degrees tilt. Each of these monkeys had maximal vergence when its nose was pointed close to upward (gravity back; mean phase: -0.9 degree +/- 26 degrees). After space flight, the modulation in vergence was reduced by over 50% for the two flight monkeys, but the phase of vergence modulation was not altered. The reduction in vergence modulation was sustained for the 11-day postflight testing period. We conclude that changes in vergence are induced in monkeys by the sinusoidal component of gravity acting along the naso-occipital axis during yaw axis OVAR, and that the modulation of the vergence reflex is significantly less sensitive to linear acceleration after space flight.

Aspiration as a guide to sepsis in revision total hip arthroplasty

One hundred sixty-five patients underwent 171 preoperative aspiration arthrograms to evaluate a painful total hip arthroplasty. Intraoperative cultures and histologic specimens were obtained in all cases. Of the 166 aspirations where fluid was obtained, there were 140 true negative, 5 true positive, 18 false positive, and 3 false negative cultures. Sensitivity of hip aspiration to identify periprosthetic sepsis correctly was 50%; specificity was 88%. Hip aspiration with a 50% sensitivity rate lacks the ability to consistently predict those patients with occult periprosthetic sepsis. The routine use of aspiration in evaluation of a painful total hip is probably not indicated. Selective use in patients with a history of wound healing problems, radiographic changes, and elevated laboratory values should be considered.

Abnormal sperm morphology is highly predictive of pregnancy outcome during controlled ovarian hyperstimulation and intrauterine insemination

PURPOSE

The purpose of this study was to assess the predictive value of a modified form of Kruger's strict criteria for sperm morphology for pregnancy outcomes after intrauterine insemination (IUI) and controlled ovarian hyperstimulation (COH) in the presence of normal sperm concentration and motility.

MATERIALS AND METHODS

A retrospective review of 42 couples undergoing COH/IUI was stratified by favorable or unfavorable sperm morphology. End points were pregnancy or failure of treatment as defined by four or more cycles of COH/ IUI without pregnancy.

RESULTS

An unfavorable morphology (< 4%) was highly predictive of failure during COH-IUI (94.45%; 17/18). A normal PIF was a sensitive indicator of those patients who became pregnant (93.8%; 15/16) and had a fair specificity for failure to achieve pregnancy after four cycles of treatment (65.4%; 17/26). Couples with a favorable sperm morphology were 28.3 times as likely to achieve a pregnancy within four cycles of treatment as those with unfavorable sperm morphology [95% confidence limits, 3.2 to 250.5; P < 0.001].

CONCLUSIONS

Abnormal strict morphologic assessment is both sensitive and specific for pregnancy outcomes in couples undergoing COH/IUI. Couples with persistently unfavorable sperm morphology should be counseled appropriately and would be better served by more aggressive treatment with in vitro fertilization and embryo transfer.

Sonographic prediction of shoulder dystocia in infants of diabetic mothers

OBJECTIVE

To determine if the difference between the abdominal diameter and biparietal diameter (AD-BPD difference), as measured by ultrasound examination, predicts shoulder dystocia in borderline macrosomic infants of diabetic mothers.

METHODS

A retrospective study was performed of births occurring from January 1990 through June 1995. Eligibility requirements included diabetic pregnancy, ultrasound examination within 2 weeks of delivery, estimated fetal weight of 3800-4200 g, and vaginal delivery. The mean AD-BPD difference was compared in normal deliveries and those complicated by shoulder dystocia, using the Student t test and by multiple regression analysis. A receiver operating characteristic curve was generated to determine if an AD-BPD cutoff value could be used clinically to predict shoulder dystocia.

RESULTS

Thirty-one patients, six with dystocia, were eligible for the study. The mean AD-BPD differences for those with and without shoulder dystocia were 3.1 and 2.6 cm, respectively, a statistically significant difference (P = .05). Comparing the groups with and without shoulder dystocia, no significant differences could be found in mean age, parity, weight, birth weight, or gestational age. Shoulder dystocia occurred in six of 20 patients (30%) in whom the AD-BPD difference was at least 2.6 cm but in none of 11 patients in whom it was less than 2.6 cm, also a statistically significant difference (P = .05).

CONCLUSION

The AD-BPD difference was greater in borderline macrosomic fetuses of diabetic mothers who experienced shoulder dystocia than in those who had uncomplicated vaginal deliveries. Applying an AD-BPD cutoff value of 2.6 cm to this population prospectively would have provided excellent sensitivity, specificity, and predictive value in identifying those fetuses at high risk for birth injury.

Olmsted syndrome. Case report and identification of a keratin abnormality

BACKGROUND

Olmsted syndrome is a rare disorder characterized by a mutilating palmoplantar keratoderma and periorificial keratotic plaques. It begins in early childhood and is complicated by the development of painful flexion contractures, constrictions, and autoamputations of the digits. Only 11 cases of Olmsted syndrome have been reported to date. However, no biochemical abnormalities in the skin were reported in any of these cases.

OBSERVATIONS

We report the 12th case of Olmsted syndrome. In addition, we describe a keratin abnormality found in a skin specimen obtained from our patient. The specimen showed a suprabasilar staining pattern with AE1, an antibody that shows only basilar staining in normal skin.

CONCLUSION

We report the 12th case of Olmsted syndrome, review the literature, and describe a keratin abnormality that was found in our patient's skin specimen.

Modeling the organization of the linear and angular vestibulo-ocular reflexes

A one-dimensional mathematical model of the compensatory linear vestibuloocular reflex (lVOR) was developed. The model was based on the concept that to effect oculomotor compensation, linear head acceleration sensed by the otoliths must be integrated twice to form the angular position-related signal required by the motoneurons. This contradicts the postulate that linear acceleration is differentiated to generate "jerk," which is then used to drive the compensatory lVOR. The transfer characteristics of different otolith afferent classes were modeled by a transfer function with a common modal structure and different degrees of compensation. Both the time and frequency domain behavior of regular and irregular otolith afferents were simulated. The outputs of the various afferent classes were superposed by a linear filter to generate the velocity command which drives the oculomotor velocity-position integrator. The model was used to simulate the dominant gain and phase characteristics of the compensatory lVOR in monkey and the dynamic characteristics of the compensatory human lVOR response for brief periods of linear acceleration on a sled. The model was then combined with the velocity storage-based model of the angular vestibulo-ocular reflex (aVOR) to simulate the eye velocity response to centrifugation in monkey and man. The model suggests that the orientation response that modifies the time constants of the velocity storage integrator is the dominant aspect of the response to linear acceleration in monkey. Human responses, on the other hand, are dominated by an effect of the beating field, which modifies the eye velocity command to the oculomotor system.

Genetic selection of peptide aptamers that recognize and inhibit cyclin-dependent kinase 2

A network of interacting proteins controls the activity of cyclin-dependent kinase 2 (Cdk2) (refs 1,2) and governs the entry of higher eukaryotic cells into S phase. Analysis of this and other genetic regulatory networks would be facilitated by intracellular reagents that recognize specific targets and inhibit specific network connections. We report here the expression of a combinatorial library of constrained 20-residue peptides displayed by the active-site loop of Escherichia coli thioredoxin, and the use of a two-hybrid system to select those that bind human Cdk2. These peptide aptamers were designed to mimic the recognition function of the complementarity-determining regions of immunoglobulins. The aptamers recognized different epitopes on the Cdk2 surface with equilibrium dissociation constant in the nanomolar range; those tested inhibited Cdk2 activity. Our results show that peptide aptamers bear some analogies with monoclonal antibodies, with the advantages that they are isolated together with their coding genes, that their small size should allow their structures to be solved, and that they are designated to function inside cells.