Pectoralis major myocutaneous reconstruction of the anterior skull base

It was once believed that prognosis for many patients with neoplasms of the anterior skull base was hopeless. Now, however, craniofacial resection of these lesions has been curative for many patients. Massive resections of the anterior skull base pose many potentially life-threatening complications. Cerebrospinal fluid leakage with meningitis is especially troublesome when previous radiation therapy compromises wound healing. In such circumstances local tissue flaps and skin grafting may not provide reliable separation of the brain from the nose. The pectoralis major flap was utilized in eight patients undergoing anterolateral resection of the skull base. Several major advantages of this technique include: 1. reliable closure of the subarachnoid space; 2. acceptable cosmesis; 3. rapid wound rehabilitation, allowing early postoperative radiation therapy when necessary.     

Dehydrohalogenation of atmospheric contaminants in the space cabin

A total of nine chlorinated ethanes and ethenes were circulated over lithium hydroxide in a laboratory scale closed system simulator. System volume and lithium hydroxide temperature were varied from that intended to maximize possible reactions to conditions approximating those of a space cabin environment. Of the nine compounds tested, seven were found to be dehydrohalogenated (viz., loss of hydrogen chloride) in the course of one or more experimental treatments. Of particular significance was the conversion of 1,2-dichloroethane to chloroethene, a known carcinogen, and of trichloroethene to dichloroethyne, a highly toxic substance. It is therefore concluded that a potentially hazardous situation exists for the inhabitants of closed ecological systems such as spacecraft, one for which precautions must continue to be taken.     

The normal range: a concept in transition

One of the most frequent and perhaps frustrating questions the pathologist is called on to answer regarding laboratory tests is, "What is normal?" In recent years the term "normal range" has been replaced by "reference range." "Upper limit of normal" has been replaced by "referent value," "critical value," or "cut-off point." Our literature now reflects increasing contributions from biostatistics, decision theory, and systems analysis. Yet, for most of us, although the names have changed, the problem has not. Understanding Bayes' Theorum will not help the busy internist when he complains about false-positive elevations in alkaline phosphatase activity on hospital admission profiles. The laboratory director must be able to integrate reference range data and predictive value theory in his own environment if he wishes to provide meaningful information to clinicians. It is the objective of this review to focus on the definition and integration of these areas of emerging concern for the laboratorian.     

Participant-centered adaptations in caregiver trials: strategies for managing confounds

BACKGROUND: Randomized trials have been criticized for being more protocol than participant-centered, with concerns raised about higher subject attrition and limited generalizability under controlled conditions. Informal caregivers are similar to other participants in community-based trials: many are unlikely to remain in a trial without procedural adaptations to meet some of their needs. PURPOSE: This article discusses design and statistical strategies for tracking potential confounds associated with 3 participant-centered adaptations that may be made in community-based caregiver trials: tailoring multi-component interventions, using interpersonal contacts for participant maintenance, and non-blinding of trial participants. The intent of the article is to initiate dialogue on the seldom-discussed issue of participant-centered adaptations in community-based trials. CONCLUSIONS: Participant-centered adaptations may reduce subject attrition and enhance generalizability, but protocol adaptation can compromise trial integrity. The challenge for investigators is to develop scientifically sound methods for tracking / controlling potential confounds associated with each adaptation.     

A rodent model for artificial gravity: VOR adaptation and Fos expression

Vestibulo-ocular reflex (VOR) adaptation and brainstem Fos expression as a result of short radius cross-coupling stimuli were investigated to find neural correlates of the inherent Coriolis force asymmetry from an artificial gravity (AG) environment. Head-fixed gerbils (Meriones unguiculatus, N=79) were exposed, in the dark, to 60--90 minutes of cross-coupled rotations, combinations of pitch (or roll) and yaw rotation, while binocular horizontal, vertical, and torsional eye position were determined using infrared video-oculography. Centripetal acceleration in combination with angular cross-coupling was also studied. Simultaneous sinusoidal rotations in two planes (yaw with roll or pitch) provided a net symmetrical stimulus for the right and left labyrinths. In contrast, a constant velocity yaw rotation during sinusoidal roll or pitch provided the asymmetric stimulus model for AG. We found orthogonally oriented half-cycle VOR gain changes. The results depended on the direction of horizontal rotation during asymmetrical cross-coupling, and other aspects of the stimulus, including the phase relationship between the two rotational inputs, the symmetry of the stimulus, and training. Fos expression also revealed laterality differences in the prepositus and inferior olivary C subnucleus. In contrast the inferior olivary beta and ventrolateral outgrowth were labeled bilaterally. Additional cross-coupling dependent labeling was found in the flocculus, hippocampus, and several cortical regions, including the perirhinal and temporal association cortices. Analyses showed significant differences across the brain regions for several factors (symmetry, rotation velocity and direction, the presence of centripetal acceleration or a visual surround, and training). Finally, animals compensating from a unilateral surgical labyrinthectomy who received multiple cross-coupling training sessions had improved half-cycle VOR gain in the ipsilateral eye with head rotation toward the intact side. We hypothesize that cross-coupling vestibular training can benefit aspects of motor recovery or performance.     

Development of a symptom assessment instrument for chronic hemodialysis patients: the Dialysis Symptom Index

Little is known about the prevalence, severity, or impact of symptoms in hemodialysis patients because of the lack of a validated symptom assessment instrument. We systematically developed an index to assess physical and emotional symptom burden in this patient population. We employed four steps in the generation of this index: a review of dialysis quality-of-life instruments, three focus groups, experts' content validity assessment, and test-retest reliability measurement. Seventy-five symptoms were identified. Of these, 46 appeared in > or = 4 of the instruments/focus groups and were considered for inclusion. Twelve were grouped into other symptom constructs and experts judged four of the remaining items not to be pertinent, leaving 30 items in the new index. Overall kappa statistic was 0.48+/-0.22. These steps allowed the systematic development of a 30-item symptom assessment index for hemodialysis patients. Additional reliability and validity testing is needed prior to its widespread use.     

Panniculectomy as an adjuvant to bariatric surgery

A large hanging panniculus can cause problems such as intertrigo, chronic infection, and immobility. Many patients undergoing weight reduction surgery can benefit from panniculectomy either done concomitantly with bariatric surgery or later after significant weight reduction. Over the last 5 years we performed 123 panniculectomies on patients (34 males, 89 females; mean age 44.5 +/- 10.3 years) undergoing bariatric surgery. The panniculectomy was either done at the same time as the bariatric surgery in 21 patients or after a time period of 17 +/- 11 months in 102 patients. The prebariatric surgery weight ranged from 107 to 341 kg (mean: 168.6 +/- 47.2 kg) with a mean body mass index (BMI) of 59 +/- 14 kg/m. After the bariatric surgery the patients had an average weight loss of 57.6 +/- 27 kg. The prepanniculectomy weight was 121.9 +/- 39.3 kg (BMI = 43.1 +/- 12.4 kg/m) for the patients who had the panniculectomy after the bariatric surgery. Ninety-two percent of the patients had multiple comorbidities. The weight of the panniculectomy specimen ranged from 4 to 54 kg. Any abdominal wall hernias (35.4% incisional and 8.9% umbilical) were fixed during the panniculectomy. Overall, patients who had panniculectomy simultaneously with the bariatric surgery had more complications than patients who had panniculectomy after their bariatric surgery. The wound infections were 48% versus 16% and respiratory distress was 24% versus 0%, respectively. The skin necrosis was 10% versus 6%, dehiscence was 33% versus 13%, and hematoma formation was 10% versus 2%, respectively. Overall, the patients had good outcomes, with 3 postoperative deaths in the group with panniculectomy at the same time of bariatric surgery. An interval of weight loss prior to the procedure makes this procedure safer and more effective.