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S R Cohen

Publications and source records attributed to S R Cohen.

At least 19 recordsLinked to original sources
PubMed2006

Sequence dependence of charge transport properties of DNA.

The electrical conduction through three short oligomers (26 base pairs, 8 nm long) with differing numbers of GC base pairs was measured. One strand is poly(A)-poly(T), which is entirely devoid of GC base pairs. Of the two additional strands, one contains 8 and the other 14 GC base pairs. The oligomers were adsorbed on a gold substrate on one side and to a gold nanoparticle on the other side. Conducting atomic force microscope was used for obtaining the current versus voltage curves. We found that in all cases the DNA behaves as a wide band-gap semiconductor, with width depending on the number of GC base pairs. As this number increases, the band-gap narrows. For applied voltages exceeding the band-gap, the current density rises dramatically. The rise becomes sharper with increasing number of GC base pairs, reaching more than 1 nA/nm2 for the oligomer containing 14 GC pairs.

Base Composition↗
PubMed2001

Lymphedema: strategies for management.

An important sequela of cancer treatment is lymphedema. Management of this condition must be based on the physiologic functioning of the lymphatic system and tailored to the individual patient's presentation of the disease. Early diagnosis and treatment are essential to prevent worsening of the condition and to help assuage the psychologic impact of the disease. A review of the normal and impaired lymphatic system is presented in this article. Current assessment and treatment options are described, including education of patients in precautions, positioning, exercise, compression garments and bandages, pneumatic pumps, and lymphatic massage. Also included is a discussion of the psychologic impact of the disease as well as management of psychologic symptoms. Various strategies for management of the physical aspects of lymphedema are available. Studies have shown that use of physical treatments such as exercise, compression, and lymphatic massage are effective in reducing the amount of swelling in affected limbs. The specific type, amount, and combination of these treatments continues to be debated. The development of lymphedema is commonly associated with significant psychologic distress that can impact on compliance with physical treatments. Because there is no consensus as to the optimal treatment approach for management of lymphedema, additional research must ensue to determine the efficacy of existing treatments and to develop new management techniques. Clinicians must be attuned to the signs and symptoms of lymphedema in order to make prompt referrals for treatment.

Bandages↗
PubMed2001

Internal Le Fort III distraction with biodegradable devices.

Shortly after the initial application of distraction osteogenesis to the human mandible by McCarthy, distraction osteogenesis was used for gradual lengthening of the midface in children with syndromic craniosynostosis, cleft lip and palate, hemifacial microsomia, and midface hypoplasia from other causes. Both external and internal devices are available for midface distraction. In spite of the many advantages of internal metallic distraction devices, they can be more difficult to remove. By substituting the metallic fixation plates of the Stryker-Leibinger Modular Internal Distraction system, with resorbable MacroPore fixation mesh, only the distractor screw and cable drive need to be removed. Moreover, by using a resorbable stabilizer, the screw and cable components are not needed for the consolidation phase, and can be removed at the completion of active distraction. In this case report of a 4-year-old girl with Crouzon's syndrome, contouring of the resorbable distraction devices was performed using a sterilizable model, 20 mm of distraction was achieved, and 4 days later the distractor screw was replaced with a resorbable stabilizer, resulting in an excellent correction of her midface hypoplasia.

Absorbable Implants↗
PubMed2001

Outcome analysis for correction of single suture craniosynostosis using resorbable fixation.

A retrospective review was performed on 63 patients at Childrens Healthcare of Atlanta at Scottish Rite who underwent correction of single-suture craniosynostosis using a resorbable fixation system. Included in the series were 24 patients with metopic synostosis, 15 with sagittal synostosis, and 24 with unicoronal synostosis. The average age at operation was 22.7 months (range: 2.8 months-18 years), and mean follow-up time was 30.7 months (range: 7.1-10 years). Reoperation equal to or exceeding the magnitude of the original procedure occurred in 4.76% of the patients. This was comparable to the reoperation rate observed at our institution using traditional fixation systems. Minor complications related to the use of resorbable plates were also identified, and the final outcome for single-suture synostosis was favorable. Results suggest that resorbable plates and screws are as effective as titanium-based systems in the treatment of single-suture synostosis.

Absorbable Implants↗
PubMed2001

Tacks: a new technique for craniofacial fixation.

Biodegradable fixation in craniofacial surgery provides secure fixation while eliminating much of the concern over intracranial migration of metallic plates and screws. One limitation of present biodegradable systems, however, is the need for tapping the drill hole before screw insertion. Herein, a new method of rigid, biodegradable fixation with tacks (Macrapore, Inc., San Diego, CA) is described. The tacks are made of a 70:30 ratio of the L and DL form of polylactic acid (L,DL-PLA). Degradation times range from 18 to 36 months. Newer prototypes are nearly developed for more rapid dissolution times. From April 1999 to February 2000, tack fixation has been applied in 100 patients (51 males, 49 females aged 3 months to 61 years). Indications for operation were craniosynostosis (n = 33); craniofacial trauma or post-traumatic deformities (n = 11); cleft lip and palate (n = 13); craniofacial syndromes (n = 18); other diagnoses (n = 11). Patients underwent fronto-orbital advancement with cranial reshaping; monobloc osteotomy, open reduction-internal fixation of fractures; hypertelorbitism repair; cranioplasty; stabilization of grafts; major cranial reconstruction; zygomatic advancement; alveolar cleft repair; and iliac bone graft donor site protection. Tacks were also used for temporalis muscle and lateral canthal suspension. Follow-up ranged from 16 to 28 months. Complications occurred in 7 patients, 4 of whom had infections and during debridement had biodegradable implants removed. None of the complications appeared to be related to the use of tacks. The tacks are carried in a specially designed holder and may be placed by hand or with the light tap of a mallet on the tack driver. An automatic driver has been developed. Overall, the performance of the tacks has been excellent. They are easily handled by the nursing personnel and rapidly inserted by the surgeon. Stability appears to be excellent. At this time, it is probably preferable to employ tap and screws for orthognathic surgery or other osteotomies with substantial load bearing.

Absorbable Implants↗
PubMed2001

A classification of facial wrinkles.

An increasing number of injectable filler materials for facial wrinkles and folds points to the need for objective measurements of their effectiveness. Patient satisfaction is the goal, but proof of the value of a particular product requires objective measurement. A wrinkle assessment scale was developed as a simple tool for use by plastic surgeons, dermatologists, and aesthetic surgeons who want to assess the changes resulting from injecting filler materials in their patients. By correlating the grade of the wrinkle in the reference photographs with the wrinkle in a patient's face, a classification of 0 to 5 is assigned. Reliability of the scale was assessed by "live" judgment of 76 wrinkles by nine observers. The same rating was given to 92.7 percent of all wrinkles. In a second trial, photographs from 130 wrinkles were presented to eight observers who rated 89.4 percent of all wrinkles equally. A significant correlation of 87 percent was found between subjective ratings and objective wrinkle depth measured by profilometry on 40 silicone impressions. Manufacturers, monitors of clinical trials, health authorities, and most important, patients will benefit from objective data on current and new injectable materials.

Absorbable Implants↗
PubMed2001

Changes in quality of life following admission to palliative care units.

The primary goal of palliative care is to improve the quality of life (QOL) of people with a terminal illness. Previous studies of the impact of hospice/palliative care have documented improvement in physical and psychological symptoms, but not in overall QOL, due in part to the difficulties of measuring QOL. The McGill Quality of Life Questionnaire (MQOL) was developed to assess QOL in persons with advanced illness. MQOL scores were determined on admission and 7-8 days later for sequential eligible and willing patients admitted to five palliative care units. These 88 patients represented 8% of those admitted to the units during the study period. Following the final MQOL completion, patients were interviewed and asked to describe the nature of the changes in QOL they had experienced since admission. Significant improvements were found in the MQOL total score and subscale scores reflecting physical, psychological and existential well-being. In the interviews patients indicated that they had experienced changes in physical, emotional and interpersonal status, in spiritual outlook, and in their preparation for death. They also described the impact of the palliative care unit environment. This is the first study to demonstrate that hospice/palliative care can improve existential well-being in addition to psychological and physical symptoms. It provides evidence in the patients' own words that improvements in QOL go beyond symptom control following admission to a palliative care unit. However, the study results are generalizable only to those few patients admitted who are well enough to complete a questionnaire 1 week after admission.

Adult↗
PubMed2000

Living with cancer: "good" days and "bad" days--what produces them? Can the McGill quality of life questionnaire distinguish between them?

BACKGROUND: To determine the impact of care on quality of life (QOL), or to detect a change in QOL over time, measures of QOL must remain stable when QOL is stable (test-retest reliability) and change when QOL changes (responsiveness). This study addresses these issues for the McGill Quality of Life Questionnaire (MQOL). Unlike other studies that use disease status to indicate whether QOL has remained stable or changed, in this study the patient determines QOL stability or change. The authors also sought to clarify the determinants of "good" and "bad" days for oncology patients. METHODS: Patients attending an oncology outpatient clinic or who were being treated by a palliative care service were asked to complete MQOL 4 times: on days they judged to be "good," "average," and "bad" and 2 days after the first completion. They also were asked to directly rate the change in their QOL during the intervals between MQOL completion and to report the most important determinants of their good and bad days. RESULTS: The test-retest reliability of MQOL as measured by an intraclass correlation coefficient ranged from 0.69 to 0.78. All MQOL scores were significantly different on good, average, and bad days, except for the support subscale, in both clinical settings. Five domains were determinants of QOL: physical symptoms, physical functioning, psychologic well-being, existential well-being, and relationships. CONCLUSIONS: MQOL's reliability and responsiveness suggest it can be used to determine changes in the QOL of groups. The results allow interpretation of changes in MQOL scores with respect to meaning of the change to oncology patients. This in turn is helpful to determine the sample size required in future studies. Some of the domains important to the QOL of oncology patients are not included in widely used measures of QOL.

Anxiety↗
PubMed2000

Intralesional laser therapy of extensive hemangiomas in 100 consecutive pediatric patients.

The authors have treated 100 consecutive pediatric patients with capillary/cavernous hemangiomas (age range, 1.3 months to 16 years; mean age, 26.6 months; 30 male and 70 female patients) with intralesional laser therapy during a 3-year period. All patients have been followed for a minimum of 6 months after treatment (range, 6-36 months; mean, 18 months). Indications for intralesional laser treatment included interference with vision, blockage of the nose or mouth, ulceration, bleeding, and rapid, uncontrollable growth. The Nd:YAG laser was used in 70 patients, and the Potassium, Titanyl, Phosphate (KTP) laser was used in 30 patients. Fifty-five hemangiomas were in the head and neck region, excluding the orbit; 25 were in the trunk or extremities; 10 were periorbital; and 10 involved multiple sites. Seventy patients (70%) received one treatment, 20 patients (20%) received two treatments, 7 patients (7%) received three treatments, and 3 patients (3%) received four or more treatments. No appreciable differences were noted between treatment with the Nd:YAG and KTP lasers. Forty-six patients had more than a 90% reduction in the overall size of the hemangiomas whereas 54 patients had a 50% to 90% reduction in the size of the hemangioma. After maximal reduction in size of the cavernous component was achieved, the external capillary component, found in 68 patients, was treated with a tunable dye laser. Seventy-six patients underwent surgical resection after maximal lesion involution. Residual induration due to lesion fibrosis was treated with local steroid injections in 13 patients. There were four operative complications attributable to intralesional laser therapy. Two patients had residual midfacial weakness, and two patients had punctuated skin burns after intralesional treatment. The authors have found intralesional laser therapy to be a valuable tool in the treatment of large capillary/cavernous hemangiomas, often rendering an inoperable lesion safely resectable, or markedly decreasing the size and functional impact of the lesion.

Adolescent↗
PubMed2000

Internal craniofacial distraction with biodegradable devices: early stabilization and protected bone regeneration.

Internal craniofacial distraction has several advantages over distraction with external devices. The scars may be less conspicuous; the devices are buried and therefore easier for patients to tolerate; and the devices are more rigidly secured to bone, preventing uncontrolled rotation of the advancing segments. There are several types of internal devices. The Modular Internal Distraction System developed by one of the authors (S.R.C.) and Stryker-Leibinger, Inc. has had widespread use for midface distraction, but requires a substantial surgical procedure for device removal. This is justified in selected children with syndromic craniosynostosis, who frequently need secondary orbitocranial reconstruction at the conclusion of distraction with any type of device. It would be preferable to develop a device that would retain the positive characteristics of the Modular Internal Distraction system, while allowing easy removability. Moreover, the entire distraction procedure would benefit from a technique that would assist in bone regeneration within the distraction gap. Such a biodegradable, stabilizing device may enable early explanation, accelerating the recovery period, while providing fixation of the distraction gap and protected bone regeneration. Accordingly, we have developed a new, biodegradable distraction device with Macropore, Inc. that may be used with the Modular Internal Distraction system to permit easy removability of the device without the need for a large operation for exposure. Second, we have developed a biodegradable stabilizer that permits earlier removal of the distraction device while providing simultaneous fixation and protected bone regeneration. Last, we have demonstrated the feasibility of midcourse correction of the distraction procedure, should this be necessary for whatever reason.

Absorbable Implants↗
PubMed2000

Iliac crest bone graft harvesting techniques: a comparison.

This study was undertaken to compare the morbidity of traditional iliac bone graft harvesting techniques for grafting alveolar clefts to minimally invasive techniques. Fifty-five age-matched patients, ages 6.5 to 16 years (mean, 11.2 years), 22 girls and 33 boys, were divided into three groups. The traditional bone window open harvesting technique served as the control group. Two different minimally invasive techniques, one that used a bone grinder and another that used a trephine, for bone harvesting were compared with the control. Both invasive techniques were statistically superior, p < 0.05, in terms of total time pain medication was necessary (mean of 12.0 hours for bone grinder, 17.6 hours for trephine, 26.0 hours for control), operative time for bone harvest (mean of 11 minutes for bone grinder and trephine, 20 minute for control), and mean incision length (2 cm for bone grinder and trephine, 5 cm for control). Patients exposed to the minimally invasive techniques had fewer complications, a trend toward earlier ambulation, and shorter hospital stays when compared with the bone grinder technique. The patients exposed to the bone grinder demonstrated earlier ambulation and fewer requirements for analgesia when compared with the trephine technique, although these results did not reach statistical significance. The trephine technique was useful when maxillary osteotomies were combined with alveolar bone grafting, because it provided structural bone grafts and cancellous bone. On the basis of these findings, the bone grinder is the preferred technique for harvesting alveolar bone grafts when no structural support is required. These authors no longer use the traditional bone window open harvesting technique.

Adolescent↗
PubMed2000

Chiari malformation, cervical spine anomalies, and neurologic deficits in velocardiofacial syndrome.

The purpose of this investigation was to evaluate the prevalence of Chiari malformation, cervical spine anomalies, and neurologic deficits in patients with velocardio-facial syndrome. This study was a prospective evaluation of 41 consecutive patients with velocardiofacial syndrome, documented by fluorescence in situ hybridization, between March of 1994 and September of 1998. The 23 girls and 18 boys ranged in age from 0.5 to 15.2 years, with a mean age of 6.7 years. Nineteen patients were assessed with magnetic resonance imaging, 39 underwent lateral cephalometric radiography, and all patients were examined for neurologic deficits. Eight of 19 patients (42 percent) had anomalies of the craniovertebral junction, including Chiari type I malformations (n = 4), occipitalization of the atlas (n = 3), and narrowing of the foramen magnum (n = 1). One patient with Chiari malformation required suboccipital craniectomy with laminectomy and decompression. Fourteen of 41 patients (34 percent) had demonstrated neurologic deficits; 10 patients (24 percent) had velar paresis (6 unilateral and 4 bilateral). Chiari malformations, cervical spine anomalies, and neurologic deficits are common in velocardiofacial syndrome. Because these findings may influence the outcome of surgical intervention, routine assessment of patients with velocardiofacial syndrome should include careful orofacial examination, lateral cephalometric radiography, and magnetic resonance imaging of the craniovertebral junction.

Adolescent↗
PubMed1999

Alternatives to tracheostomy in infants and children with obstructive sleep apnea.

PURPOSE: Since 1989, 70 children have been treated surgically with varying degrees of obstructive sleep apnea (OSA). Of these, 29 patients had completely failed conventional medical and surgical treatment and were considered tracheostomy (T) candidates, whereas five had previously undergone T for severe OSA as infants and did not respond to standard decannulation protocols. The preoperative diagnoses were cerebral palsy (n = 5), Down's syndrome (n = 5), hemifacial microsomia (n = 4), Pierre Robin sequence (n = 6), and a mixed group of craniofacial disorders (n = 14). The patients ranged in age from 2.5 weeks to > or =18 months (mean, 7.32 years). Preoperatively, four patients were on ventilators and one suffered a cardiac arrest, attesting to the severity of OSA. METHODS: To enlarge the caliber of the airway, each patient underwent an aggressive surgical treatment protocol. All sites of upper airway obstruction were treated simultaneously by a combination of craniofacial skeletal expansion and soft-tissue reduction. RESULTS: Tracheostomy was avoided in 90.4% of patients. Temporary or "permanent T" were required in three patients (9.6%). One patient with cerebral palsy had recurrent OSA and died. A second patient with severe laryngotracheomalacia and retrognathia who did not respond to apnea surgery underwent a tracheostomy and ultimately died of pulmonary causes. Four patients (7.8%) required supplemental home oxygen or continuous positive airway pressure. The average preoperative respiratory disturbance index, defined as the average number of apneic and hypopneic events per hour of sleep, dropped from 25.9 to 4.4 after surgery. The average lowest recorded oxygen saturation during overnight polysomnography rose from 61% to 92% after surgery. Of the five patients with permanent T, four had thus far been decannulated. Complications occurred in 10 patients, 50% of which were related to minor problems with mandibular distraction devices. CONCLUSION: Our results confirm the efficacy of an aggressive surgical approach to the treatment of OSA in children, avoiding the necessity for tracheostomy or permitting decannulation of permanent T in the majority of cases.

Child↗
PubMed1999

Midface distraction.

Since the initial application of distraction osteogenesis to the human mandible by McCarthy, distraction osteogenesis has been used for gradual lengthening of the midface in children with syndromic craniosynostosis, cleft lip and palate, hemifacial microsomia, and midface hypoplasia from other causes. Both external and internal devices are available that permit midface distraction. The background of midface distraction and the development of a Modular Internal Distraction (MID) system that permits widespread use of easily customized, buried distraction devices throughout the craniofacial region are presented. The relative and potential clinical indications for distraction, treatment planning, patient preparation, and possible surgical orthodontic interactions during distraction, as well as a variety of case examples showing the MID system, are discussed.

Acrocephalosyndactylia↗
PubMed1999

Monobloc and facial bipartition distraction with internal devices.

Distraction osteogenesis (DO) permits gradual lengthening of the craniofacial skeleton. With the advent of new internal devices, monobloc (M) and facial bipartition (FB) DO are feasible. The rationale behind M and FB distraction is (1) gradual advancement of the M segment is not associated with a substantial retrofrontal dead space; (2) because 5 to 7 days elapse prior to distraction, the nasofrontal opening, in theory, is allowed to remucosalize; (3) gradual expansion of the soft tissues takes advantage of skin creep, potentially limiting relapse; (4) the procedure appears to be less invasive with decreased blood loss and operative time, enabling its use in infants; (5) overdistraction may eliminate or reduce the frequency of subsequent procedures; and (6) the procedure may be combined with FB and skull vault remodeling to provide excellent results in more complex craniofacial dysostosis problems. Five children underwent M advancement (N = 3) and M with FB (N = 2) at 9 months to 5 years of age to correct functional abnormalities such as corneal exposure, increased intracranial pressure, and apnea, as well as severe craniofacial disfigurement. Each patient underwent from 22 to 30 mm of distraction with the Modular Internal Distraction (MID) system, developed by the first author (SRC). There was one infection late in the series along the DO cable track. There were no cases of epidural abscess. In conclusion, MDO, with and without FB, appears to be a safe and effective technique for transcranial frontofacial advancement. The morbidity of the procedure appears to be less than that of conventional M advancement.

Acrocephalosyndactylia↗
PubMed1999

Airway disorders in hemifacial microsomia.

The anatomic components of hemifacial microsomia have been classified previously, but their relevance to functional abnormalities has not been stressed. In a recent review of the literature, we found that the frequency and severity of airway disorders, especially those leading to upper airway obstruction and/or obstructive sleep apnea, had not been reported. Accordingly, a retrospective study of 38 patients (21 male, 17 female), aged 6 months to 22 years (mean, 8 years 3 months) with hemifacial microsomia was undertaken to ascertain the frequency and severity of airway disorders in hemifacial microsomia. Upper airway disorders fell broadly within three categories: group I (n = 22, 58 percent) was asymptomatic for airway disturbances; group II (n = 7, 18 percent) had a medical history suspect for intermittent obstructive sleep apnea or had a perioperative apneic event; and group III (n = 9, 24 percent) had a definite history of obstructive sleep apnea or upper airway obstruction requiring tracheotomy or apnea surgery. Group III versus groups II and I had a higher incidence of bilateral involvement (33 percent versus 14 percent and none), a greater percentage of M2, M2a, M2b, and M3 mandibular deformities (88.9 percent versus 28.6 percent and 18.2 percent), more severe orbital involvement (33 percent O2 and O3 versus none in group II and 9 percent in group I), and more severe soft-tissue involvement (89 percent S2 and S3 versus 29 percent and 23 percent). Patients with more severe mandibular and orbital deformities, but not ear or vertebral abnormalities, appear at a greater risk for obstructive sleep apnea. The relationship of OMENS-Plus (extracraniofacial anomalies) to apnea was variable but was found more commonly in group II (86 percent) and group III (56 percent) than in group I (32 percent) patients. Group III patients had a higher frequency of cardiac anomalies (44 percent versus 29 percent in group II and 23 percent in group I). The incidence of obstructive sleep apnea in our population of patients with hemifacial microsomia approaches 24 percent. Patients with hemifacial microsomia should undergo routine screening for obstructive sleep apnea: a positive history warrants polysomnographic and anatomic workup.

Adolescent↗