Characterization of sterically stabilized cisplatin liposomes by nuclear magnetic resonance

Extensive scientific efforts are directed towards finding new and improved platinum anticancer agents. A promising approach is the encapsulation of cisplatin in sterically stabilized, long circulating, PEGylated 100 nm liposomes. This liposomal cisplatin (STEALTH cisplatin, formerly known as SPI-77) shows excellent stability in plasma and has a longer circulation time, greater efficacy and lower toxicity than much free cisplatin. However, so far, the physicochemical characterization of STEALTH cisplatin has been limited to size distribution, drug-to-lipid ratio and stability. Information on the physical state of the drug in the liposome aqueous phases and the drug's interaction with the liposome membrane has been lacking. This study was aimed at filling this gap. We report a multinuclear NMR study in which several techniques have been used to assess the physical nature of cisplatin in liposomal formulations and if and to what extent the drug affects the liposome phospholipids. Since NMR detects only the soluble cisplatin in the liposomes and not the insoluble drug, combining NMR and atomic absorption data enables one to determine how much of the encapsulated drug is soluble in the intraliposomal aqueous phase. Our results indicate that almost all of the cisplatin remains intact during the loading process, and that the entire liposomal drug is present in a soluble form in the internal aqueous phase of the liposomes.

Laparoscopic varicocelectomy with preservation of the testicular artery in adolescents

PURPOSE

The aim of this study was to determine if laparoscopic varicocelectomy (LV) with preservation of the testicular artery (TA) is a satisfactory alternative to standard open surgical techniques in adolescents.

METHODS

Between June 1993 and June 1999 left LV was performed on 40 boys, median age, 12 years (range, 9 to 16 years). Selection for surgical correction included size of the varicocele, symptoms, and clinical or ultrasound assessment for testicular hypotrophy. Eight patients had undergone previous left-sided inguinal surgery, 5 of these for varicocele. Three laparoscopic ports were used. The TA was identified and preserved with the aid of a Doppler flow transducer ("Smart Needle"). All the testicular veins were ligated and divided. The inferior epigastric (IE) veins also were ligated in 19 patients. The operating time was a mean of 1 hour. The postoperative follow-up for a median of 19.5 months (range, 3 to 36 months) included clinical and ultrasound assessment.

RESULTS

Preoperative assessment confirmed left-sided testicular hypotrophy 35 patients (88%). Thirty-eight varicoceles were stage 3, and 2 were stage 2. Testicular discomfort was present in 13 patients. Complete correction of the varicocele was achieved in 33 (83%). At a mean of 5 months after LV open repair in 7 patients confirmed a dilated cremasteric vein connecting to the IE veins. Ligation of the IE veins at the time of LV was associated with a persistent varicocele in 3 of 19 patients (16%), similar to the nonligated group, 4 of 21 patients (19%). Five patients (12.5%) had a mild hydrocele. The left testicular volume increased 30% to 50% in 28 patients (70%) at a median of 6.5 months after repair. Testicular atrophy did not occur in any patients. The majority of patients went home within 6 hours of surgery.

CONCLUSIONS

The laparoscopic technique with preservation of the TA is an acceptable alternative to open surgical treatment of varicoceles. Further, it eliminates the risk of testicular atrophy and is the technique of choice when previous inguinal surgery has been performed. Ligation of IE veins was not associated with a decrease in the persistence of varicocele postoperatively.

Increased semantic and repetition priming in schizophrenic patients

Positive and negative priming (PP and NP) in schizophrenia were studied with a lexical-decision task. Probe words, presented 800 ms after the response to the prime (containing a word and a nonword), were either identical to, semantically related to, or unrelated to the prime target word (PP) or to the prime distractor word (NP). Schizophrenic patients displayed stronger semantic and repetition PP than controls after controlling for their slower responses. Significant NP was observed in both groups for word repetition only. The PP findings contrast with results from studies with similar prime-probe intervals but without prime responses. It is proposed that schizophrenic patients, because of impaired (controlled) processes of response selection, strongly benefit from (or rely on) the automatic retrieval of processing episodes containing response information. Related findings indicating automatic response facilitation in schizophrenia are discussed.

Paclitaxel-based chemotherapy in carcinoma of the fallopian tube

OBJECTIVE

The objective of this study was to determine the clinical outcomes of patients with fallopian tube carcinoma treated with paclitaxel-based combination chemotherapy following primary cytoreductive surgery.

METHODS

Twenty-four patients with the diagnosis of primary tubal adenocarcinoma treated between 1993 and 1998 were identified through the gynecology service database and the Memorial Sloan-Kettering Cancer Center tumor registry. Medical records were reviewed for information on age, stage, chemotherapy regimen, surgical intervention, relapse, and survival. All patients had their histologic material initially read or reviewed at Memorial Sloan-Kettering Cancer Center prior to treatment. The original slides were reviewed again by one of the authors (P.E.S.) to confirm the diagnosis of primary fallopian tube cancer.

RESULTS

The mean age of the patients was 63 years (range, 44-76). Distribution by stage was as follows: four patients (17%) were Stage I, three patients (12%) were Stage II, 16 patients (67%) were Stage III, one patient (4%) was Stage IV. Four patients had grade 2 tumors, 20 had grade 3. Sixteen patients (67%) had optimal cytoreduction at the time of initial surgery with residual disease less than 1 cm. Eight patients (33%) had suboptimal cytoreduction. Following initial surgery, all patients were treated with paclitaxel-based chemotherapy for a median of five cycles. Twenty-three patients received paclitaxel at the dose of 135-175 mg/m(2) in combination with carboplatin or cisplatin; the majority, 17 of 23 (74%), received carboplatin. One patient received paclitaxel alone. Median follow-up from time of initial surgery was 24 months (range, 1-73 months). Two patients are dead of disease. Overall survival for the entire group was 96% at 12 months by Kaplan-Meier analysis, and 90% at 3 years. The overall median progression-free survival was 27 months (range, 5-57 months) for the entire group. The median disease progression-free survival at 3 years was 67% (95% CI, 45-100) in the optimally debulked group as compared with 45% in the suboptimally debulked group (95% CI, 27-57). Twelve patients (50%) had evidence of recurrence or persistent disease. There were fewer recurrences in the optimally debulked group: 5 of the 16 patients (31%) versus 7 of the 8 patients (88%) with suboptimal cytoreduction.

CONCLUSION

Optimally cytoreduced patients with primary fallopian tube carcinoma treated with a paclitaxel-based chemotherapy regimen have an excellent possibility of survival.

Urethral trauma in children

We report our 12-year experience in the management of urethral injuries in nine children, six boys and three girls. The most common mechanisms of injury were motor vehicle accidents, followed by straddle injuries. All the injuries in boys involved the anterior urethra, and in girls the proximal or mid-urethra. There were associated injuries in five, including three pelvic fractures. All children were investigated with a retrograde urethrogram. Four were treated non-operatively with insertion of a urethral catheter. Of the remaining five, one had drainage of a penile haematoma, one cystourethroscopy, two insertion of urinary and suprapubic catheters, and one open cystotomy and passage of a guide wire with antegrade passage of a urethral catheter. Complications included one urinary tract infection, one urethral fistula, one urethrovaginal fistula, and two urethral strictures. Final outcome was satisfactory in all nine children.

A screening process predicts success rates in residency re-training among new immigrant physicians in Israel

OBJECTIVES

To evaluate predictors of success in training programs for Israeli international medical graduates (IMGs) from the former USSR.

SUBJECTS

IMGs up to the age of 45 who passed a national licensing examination and a Hebrew knowledge exam were eligible for participation.

INTERVENTION

Each IMG participated in one of three programs that offered similar academic activities. In two programs there was a preliminary selection process and one program had supplementary teaching hours.

MAIN OUTCOME MEASURES

Resident's self-evaluation of skills compared with evaluation by department heads. The evaluation included eight clinical skills, a general evaluation, and the passing rate for Phase I of the National Certification Exam.

FINDINGS

A total of 176 IMGs, all graduates from medical schools in USSR who immigrated to Israel from 1990 to 1996, and 20 heads of the participating departments completed the questionnaires. The response rate was 64% among the residents and 71% among the department heads. All residents had a similar level of self-esteem regarding clinical skills and considered themselves equal to or better than Israeli-trained residents. The department heads did not concur with this assessment, particularly for residents who participated in the program with no preliminary selection. Participants in the programs with preliminary selection received better evaluations from department heads than those in the program without and had significantly greater success in the written part of the board certification examination (p < 0.05).

DISCUSSION AND CONCLUSIONS

Re-training programs for IMGs should include a preliminary process for participant selection. The training program should be implemented in academic departments, in which case supplementary teaching hours are not required.

Interhemispheric cooperation during word processing: evidence for callosal transfer dysfunction in schizophrenic patients

Functional lateralization and interhemispheric interaction during word processing were investigated in schizophrenic patients (n=12) and matched healthy controls (n=18). Words and phonologically regular pseudowords were presented tachistoscopically either in the left or right visual field (unilateral conditions), or simultaneously in both visual hemifields (bilateral condition). Consistent with earlier findings, healthy controls showed a right visual field advantage (RVFA), indicating left-hemispheric dominance for language. The patients showed a RVFA similar to that of controls, consistent with normal left-hemispheric language dominance. Importantly, controls performed much better on words presented in the bilateral condition, when two copies of the same word appeared twice, compared to stimulation in only one of the visual hemifields. This bilateral advantage, which has been interpreted as evidence for cooperation between the hemispheres, was absent in schizophrenics. These data show that schizophrenic patients can exhibit similar lateralization patterns as healthy controls. Their specific functional deficit may be a lack of cooperation between the hemispheres.

Event-related potentials in a working-memory task in schizophrenics and controls

Event-related potentials (ERPs) were recorded from 65 channels in 12 schizophrenics and 12 age- and sex-matched controls during a delayed matching-to-sample design with variation of working-memory (WM) challenge: following a 500 ms visual sample stimulus (called S1, two diamonds varying in size, rotation angle and vertical position), the same pattern was either presented throughout a 6s retention interval (no challenge) or a diamond pattern differing from the first one in at least one dimension was presented during this interval (WM challenge). The 500 ms matching stimulus (called S2) comprised one diamond, which had to be matched for identity to either the left or the right diamond of the sample stimulus. The topographical distribution of ERPs during an interval of 500 ms after S1-onset, 5s of the retention interval, a 500 ms-interval preceding the S2, and a 1s postimperative interval were evaluated. No WM challenge during the retention interval induced a right-posterior accentuation of the slow negative potentials in either group, while WM challenge evoked a tendency for left-hemispheric negativity in controls, but not in patients. Patients exhibited a postimperative negative variation (PINV) with left-anterior focus irrespective of the preceding WM challenge, while in controls, the left-anterior PINV was found only following WM challenge. In schizophrenic patients the lack of a left-anterior accentuation of negative ERPs under WM challenge might be related to WM dysfunction, and the condition-independent PINV might be considered either the consequence of this dysfunction or indication of processes related more to the diagnoses than to WM-challenge and -dysfunction.

Epidemiology of pneumococcal infections in French children

Since 1977, resistance to beta-lactams and other families of antibiotics among isolates of Streptococcus pneumoniae has increased alarmingly worldwide. France is particularly affected by this phenomenon; in 1997 the French National Reference Centre for Pneumococci reported that 44% of S. pneumoniae strains were penicillin non-susceptible (PNSS). Furthermore, resistance to macrolides (53%) and sulphonamides (37%) was comparable; in addition, >50% of PNSS had a high level of resistance to penicillin and were multiresistant. The highest frequency of resistance is observed in children, particularly those with acute otitis media (AOM).

CONCLUSION

The clinical consequences of increasing antibiotic resistance are evident for meningitis and AOM, prompting clinicians to consider alternative agents such as high-dose cefotaxime (300 mg/ kg/d) or ceftriaxone (100mg/kg/d) plus vancomycin (60 mg/kg/d) for meningitis, and high-dose amoxicillin (> 80 mg/kg/d) or ceftriaxone (50 mg/kg/d) for AOM.

Resilience of the internet to random breakdowns

A common property of many large networks, including the Internet, is that the connectivity of the various nodes follows a scale-free power-law distribution, P(k) = ck(-alpha). We study the stability of such networks with respect to crashes, such as random removal of sites. Our approach, based on percolation theory, leads to a general condition for the critical fraction of nodes, p(c), that needs to be removed before the network disintegrates. We show analytically and numerically that for alpha</=3 the transition never takes place, unless the network is finite. In the special case of the physical structure of the Internet (alpha approximately 2.5), we find that it is impressively robust, with p(c)>0.99.

Electroencephalographic activity over temporal brain areas during phonological encoding in picture naming

OBJECTIVES

The present study examined electroencephalographic (EEG) correlates of phonological encoding during picture naming with special emphasis on hemispheric asymmetries of these EEG correlates. We also examined whether a small set of stimuli was sufficient to study the phonological encoding, and to what extent the complexity of the produced message affects the EEG responses.

METHODS

Event-related electrical brain activity during the covert and overt production of names and nominal phrases derived from 16 variants from 4 different pictures was compared with that during passive viewing of the same pictures.

RESULTS

Topographical and source analyses of the differential EEG activity (naming versus passive viewing) indicated that the N1 and P2 components of the visual evoked potential resulted from the same brain areas, but were activated stronger during naming as compared to passive viewing. In contrast, the differential EEG activity from 275 to 400 ms suggested the involvement of additional brain areas during naming with more pronounced left- than right-hemispheric activation in middle and posterior temporal regions for both overt and covert naming.

CONCLUSIONS

Results suggest the involvement of Wernicke's area in the phonological encoding of a message during speech production, which can even be obtained with a small set of pictures and a large number of repetitions.

Parathyroid xenotransplantation without immunosuppression in experimental hypoparathyroidism: long-term in vivo function following microencapsulation with a clinically suitable alginate

Permanent hypoparathyroidism is one of the most difficult of all endocrine disorders to treat medically. Because this deficiency syndrome rarely is a life-threatening condition, systemic immunosuppression for recipients of transgenic transplants is not justified. An alternative would be protecting the tissue to be transplanted from the immunologic response (immunoisolation) by coating it with a semipermeable membrane- microencapsulation. Unfortunately, prior to the first clinical use, further analysis of the coating substance (alginate) demonstrated that it has potential cancerogenic properties. Using a purified amitogenic alginate suitable for clinical use, we accomplished allotransplantation in a long-term animal model and reported the first clinical cases without postoperative immunosuppression recently. In view of the potential clinical use, we investigated the ability of the microencapsulation technology with the novel amitogenic alginate in experimental hypoparathyroidism (80 parathyroidectomized rats) to enable transgenic transplantation across the highest immunologic barrier (xenotransplantation: human to rat) to ensure intact transplant function without immunosuppression. In a controlled, long-term animal study, the effect of microencapsulation on xenotransplanted human parathyroid tissue was evaluated over a period of 30 weeks (microencapsulated and naked hyperplastic parathyroid tissue, respectively). Functionally, human parathyroid tissue was able to replace that of rats. More than 6 months after xenotransplantation 32 of 40 animals that had received microencapsulated transplants were normocalcemic. In contrast, serum calcium concentrations dropped to postparathyroidectomy levels within 3 weeks in the animals that had received naked tissue only. Correspondingly, normocalcemic animals showed vital parathyroid tissue inside the microcapsules, which were surrounded by a small rim of fibroblasts. When combining microencapsulation with an improved tissue culture method, xenotransplantation of human parathyroid tissue and maintenance of its physiologic function is reproducibly achieved over the highest transplantation barrier. Using the amitogenic alginate may be a crucial step toward the first clinical use of this technique for parathyroid xenotransplantation without immunosuppression.

Revisiting breast masses with the plastic surgeon: suggestions for biopsy and resection

Between 250,000 and 500,000 breast mass biopsies are performed each year. This is a common procedure of the breast that should be planned such that maximum treatment is achieved with minimal disfigurement and scarring. Plastic surgery techniques must be used in the choice of biopsy site and planned excision and can result in an improved cosmetic result for the patient. Subareolar masses are resected using a radial elliptical incision. Lateral and medial masses are resected using the Wise pattern reduction mammaplasty whereas the vertical mammaplasty is used for lesions of the central inferior breast and inframammary fold. Awareness of these basic reconstructive principles by the general surgeon can minimize disfigurement and facilitate future reconstruction by the plastic surgeon so that both cure and cosmesis can be achieved.

Development and application of normal limits for left ventricular ejection fraction and volume measurements from 99mTc-sestamibi myocardial perfusion gates SPECT

Gated SPECT is a reproducible method for assessing left ventricular volume (LVV) and left ventricular ejection fraction (LVEF) from 99mTc-sestamibi myocardial perfusion imaging studies. LVV and LVEF measurements by this approach correlate well with those obtained from other cardiovascular imaging techniques. Nevertheless, the lack of criteria for abnormal test findings has limited the potential clinical application of this new imaging technique.

METHODS

Gated SPECT measurements were evaluated for 214 patients with a low Bayesian likelihood (< 10%) of coronary artery disease (CAD) before performance of 99mTc-sestamibi stress-rest myocardial perfusion SPECT. The patients were grouped into normotensive patients (n = 98), hypertensive patients without left ventricular hypertrophy (LVH) (n = 80), and hypertensive patients with LVH on resting electrocardiography (n = 36). Gated SPECT measurements for left ventricular end-diastolic volume (LVEDV) index, left ventricular end-systolic volume (LVESV) index, and LVEF were obtained according to a published method, using a modified Simpson's rule technique.

RESULTS

Similar results were obtained for mean LVV and LVEF measurements between normotensive patients and hypertensive patients without LVH. Hence, these groups were combined (as group 1). By contrast, hypertensive patients with LVH (group 2), had significantly lower LVEF values (P = 0.01) and higher mean LVESV index values than normotensive patients (P = 0.03). Sex differences were marked: women had significantly higher mean resting LVEF values than men (P < 0.0001) and significantly lower mean resting LVEDV index values (P < 0.0001). A significant relationship was seen between LVEDV index and LVEF (r = -0.60; P < 0.0001) and between LVEDV index and heart rate (r = -0.26; P < 0.001). The normal limits were LVEF > or = 41% in men and > or = 49% in women, LVEDV index < or = 76 mL/m2 in men and < or = 57 mL/m2 in women, and LVESV index < or 38 mL/m2 in men and < or =26 mL/m2 in women. Among hypertensive patients, 22% with LVH had an abnormally low LVEF and 19% had an increased LVEDV index according to these test criteria. By contrast, no hypertensive patients without LVH had an abnormally low LVEF, and only 6% had volume abnormalities.

CONCLUSION

Using a cohort of low-likelihood patients, we generated sex-specific normal limits for LVV and LVEF for myocardial perfusion gated SPECT. Application of these findings resulted in the detection of occult left ventricular dysfunction in approximately one fifth of hypertensive patients for whom concomitant LVH was found through resting electrocardiography. These normal limits can now be evaluated prospectively for their potential clinical value.

Side-to-side isoperistaltic strictureplasty in extensive Crohn's disease: a prospective longitudinal study

OBJECTIVE

To report on the results of a prospective longitudinal study of a new bowel-sparing procedure (side-to-side isoperistaltic strictureplasty [SSIS]) in patients with extensive Crohn's disease.

METHODS

Between January 1992 and April 1999, the authors operated on 469 consecutive patients for Crohn's disease of the small bowel. Seventy-one patients (15.1%) underwent at least one strictureplasty; of these, 21 (4.5%; 12 men, 9 women; mean age 39) underwent an SSIS. The long-term changes occurring in the SSIS were studied radiographically, endoscopically, and histopathologically.

RESULTS

The indication for surgical intervention was symptomatic partial intestinal obstruction in each of the 21 patients. Fourteen SSISs were constructed in the jejunum, four in the ileum, and three with ileum overlapping colon. The average length of the SSIS was 24 cm. Performance of an SSIS instead of a resection resulted in preservation of an average of 17% of small bowel length. One patient suffered a postoperative gastrointestinal hemorrhage. All patients were discharged on oral feedings after a mean of 8 days. In all cases, SSIS resulted in resolution of the preoperative symptoms. With follow-up extending to 7.5 years in 20 patients (one patient died of unrelated causes), radiographic, endoscopic, and histopathologic examination of the SSIS suggests regression of previously active Crohn's disease.

CONCLUSIONS

SSIS is a safe and effective procedure in patients with extensive Crohn's disease. The authors' results provide radiographic, endoscopic, and histopathologic evidence that active Crohn's disease regresses at the site of the SSIS.

Bilateral hemothorax revealing mediastinal parathyroid adenoma

We report the case of a 63-year-old woman admitted to hospital because of bilateral hemothorax associated with acute respiratory failure and laterotracheal neoformation. A right thoracoscopy biopsy revealed a paratracheal parathyroid adenoma which was responsible for bilateral hemothorax and primary hyperparathyroidism. A curative resection was successfully performed by cervicotomy.

Endothelial dysfunction in a murine model of mild hyperhomocyst(e)inemia

Homocysteine is a risk factor for the development of atherosclerosis and its thrombotic complications. We have employed an animal model to explore the hypothesis that an increase in reactive oxygen species and a subsequent loss of nitric oxide bioactivity contribute to endothelial dysfunction in mild hyperhomocysteinemia. We examined endothelial function and in vivo oxidant burden in mice heterozygous for a deletion in the cystathionine beta-synthase (CBS) gene, by studying isolated, precontracted aortic rings and mesenteric arterioles in situ. CBS(-/+) mice demonstrated impaired acetylcholine-induced aortic relaxation and a paradoxical vasoconstriction of mesenteric microvessels in response to superfusion of methacholine and bradykinin. Cyclic GMP accumulation following acetylcholine treatment was also impaired in isolated aortic segments from CBS(-/+) mice, but aortic relaxation and mesenteric arteriolar dilation in response to sodium nitroprusside were similar to wild-type. Plasma levels of 8-epi-PGF(2alpha) (8-IP) were somewhat increased in CBS(-/+) mice, but liver levels of 8-IP and phospholipid hydroperoxides, another marker of oxidative stress, were normal. Aortic tissue from CBS(-/+) mice also demonstrated greater superoxide production and greater immunostaining for 3-nitrotyrosine, particularly on the endothelial surface. Importantly, endothelial dysfunction appears early in CBS(-/+) mice in the absence of structural arterial abnormalities. Hence, mild hyperhomocysteinemia due to reduced CBS expression impairs endothelium-dependent vasodilation, likely due to impaired nitric oxide bioactivity, and increased oxidative stress apparently contributes to inactivating nitric oxide in chronic, mild hyperhomocysteinemia.