Impact of mandibular condyle preservation on patterns of failure in head and neck cancer.

OBJECTIVE: To determine the role of native condyle preservation in local recurrence after segmental mandibulectomy in patients with head and neck squamous cell carcinoma. METHODS: Retrospective chart review with main outcome measuring local control of cancer. RESULTS: Between 1994 and 2003, 72 patients (48 men, 24 women) with an average age of 73.5 years without previous treatment underwent segmental mandibulectomy. Fifty-four cases (n = 54) involved the mandible posterior to the mental foramen and are the subject of this review. In 36 patients, the condyle was preserved and mandibular continuity was restored. In 18 patients, condyle and ramus were resected without mandibular reconstruction. Reconstructive modalities included primary closure (3), split-thickness skin graft (3), pedicle flap (19), and free tissue reconstructions (29). Overall local-regional recurrence rate was 22 percent (12 of 54); no recurrences were identified in patients who underwent condylar resection. Recurrences were observed in patients with mandibular reconstruction by both plate and pedicle flap (5 of 9) or (osteo) myocutaneous free flap (7 of 27). CONCLUSION: Condylar preservation may predispose patients to local recurrence after segmental mandibulectomy. This does not translate into overall reduction in survival.     

Dosimetry associated with exposure to non-ionizing radiation: very low frequency to microwaves

The interpretation of the effects in biological systems exposed to electromagnetic (EM) fields requires knowledge of the internal fields and absorbed energy. The quantification of the specific absorption rate (SAR) is called dosimetry. The SAR given in units of watts per kilogram is a complex function of the source configuration, shape and size of the exposed subjects, orientation of the subject with respect to the source, and the frequency. The average and maximum SAR in the exposed subject may vary over many orders of magnitude for a given exposure level. In order to relate observed biological effects in exposed laboratory animals to safe exposure levels for man, both the fields within the environment and SAR within the exposed tissues must be determined. The environmental fields and the SAR can often be determined from EM theory, but in most cases one must rely on instrumentation such as field survey meters for quantifying the exposure fields and electric field probes, thermocouples, thermistors, fiber optic probes, thermography, and calorimetry for quantifying the SAR in the tissues or equivalent models. A combination of techniques, each valid for a particular model over a particular frequency range, have been used to determine average and peak SARs in humans and animals exposed to plane wave radiation. Though it has been considerably more difficult to quantify these quantities for near field and partial-body exposure conditions, progress is continually being made in this area.     

Lung cancer in Newfoundland, Canada

In this study 1,466 cases of primary lung cancer diagnosed between 1974 and 1983 and reported to the Provincial Tumour Registry, were reviewed. The incidence of lung cancer in Newfoundland has been lower than that in Canada as a whole. The age-adjusted rates for Canadian males and females were 56 and 14 per 100,000 compared to 45 and 7 in Newfoundland. Census division rates showed no association with socioeconomic indicators. The rate in one census division was higher (63 vs 53) most probably because of the higher risk of men who worked in the St. Lawrence fluorspar mines. Although Newfoundland's current smoking rates (39% of men over 15 and 29% of women over 15) are high, this is not reflected in lung cancer rates. Smoking was not widely accepted in rural areas until the time of World War II, and Newfoundland's lower rates may be due to this delay in exposure.     

The Physiology of Gastrocystoplasty: Once a Stomach, Always a Stomach

To determine the physiology of acid secretion after gastrocystoplasty with the body of the stomach we performed a prospective standardized 3-day study in 13 children (median age 12.5 years) who had undergone bladder augmentation/replacement (median postoperative period 2 years). Urinary pH and titratable acid, and serum gastrin levels were measured after gastric distention with a meal and bladder distention with urethral filling at baseline and after medication with a histamine-2 receptor antagonist or an anticholinergic agent. Five children underwent cystoscopy and biopsy of the gastric and native segments of the gastrocystoplasty.

In the fasting state pH was neutral, there was no titratable acid in the urine and serum gastrin level was normal in all cases. After a meal urinary acid secretion and serum gastrin level increased markedly. After each medication half of the patients demonstrated marked inhibition of urinary acid secretion after a meal while response was partial in the remainder. In none of the patients was there significant alteration in the pattern of gastrin secretion. Bladder distention did not result in urinary acid secretion or gastrin secretion. The cystoscopic and histological appearance of the native bladder and stomach segment of the gastrocystoplasty in the 5 patients was normal. We conclude that the gastric body segment used in gastrocystoplasty continues to secrete acid as though it were part of the stomach. The secretion of acid in the urine can be decreased with histamine-2 receptor antagonist or anticholinergic medication.     

Fragmentation process of current laser lithotriptors

Background and Objective: Flashlamp pumped dye (FPDL), Q-switched Nd:YAG, and alexandrite lasers are the most clinically used laser lithotriptors. Although calculi are fragmented by laser induced mechanical stresses for all lithotriptors, different fragment sizes and fragmentation efficiencies have been reported. In this work the effect of the pulse duration and pulse shape on the fragmentation processes is studied. Material and Methods: Fragmentation processes are characterized on model stones and on sensing target fibers. Stone fragmentation and cavitation bubble generation are observed by video flash photography. Shock wave occurrence and strength are monitored with an hydrophone. Results: For the FPDL, stone fragmentation is induced by the collapse of the large cavitation bubble formed. For the Q-switched Nd:YAG, fragmentation is already observed during the laser pulse, at the plasma onset, although further fragmentation can occur at the bubble collapse. For pulse durations corresponding to the alexandrite, an intermediate fragmentation regime is observed. Conclusion: For the first time the physical basis of the observed differences in the fragmentation efficiencies of current laser lithotriptors is described. For nanosecond durations the fragmentation processes are governed by plasma induced shock waves. On the contrary, for microsecond durations fragmentation is governed by cavitation. The high fragmentation efficiency of microsecond lasers is due to a high laser energy transfer into cavitation. © 1995 Wiley-Liss, Inc.     

Clinical use of a standard kit-preparation of radiolabeled monoclonal antibody 96.5 in the diagnostic imaging of metastatic melanoma

We studied the efficiency of a standard-kit preparation using 1 mg 111In-labeled 96.5 monoclonal antibody in combination with 19 mg of unlabeled antibody in the diagnostic imaging of 27 patients with documented metastatic melanoma. Twenty-three of 26 patients (88%) demonstrated immunoscintigraphic localization of tumor. Of 104 metastatic sites previously documented by conventional studies, 62 (60%) were identified by immunoscintigraphy. A total of 77 sites demonstrated localization of radiolabeled antibody. Fifty-four (70%) corresponded to known sites of disease; eight sites (10%) were "discovered" by immunoscintigraphy and subsequently confirmed by conventional studies; 15 imaged sites (20%) could not be confirmed by conventional studies. Size and location of metastasis appear to be important features that influence imaging efficiency. Tumor size (greater than or equal to 2 cm v less than 2 cm) appears to be the statistical dominant determinant. The feasibility and potential clinical use of radioimmune imaging of tumors is discussed.     

The Relationship of pK a and Acute Skin Irritation in Man

The relationship between pK _a and skin irritation in man is studied for a homologous series of benzoic acid derivatives, which permeate through human skin at comparable rates (15–88 µg/cm²/hr). Skin irritation and pK _a are correlated for pK _a 4. Laser Doppler velocimetric assessment of skin blood flow, color meter readings, erythema, edema, and the primary irritation index are all linearly correlated and related to pK _a, erythema at 24 hr appears to be the most sensitive parameter to variation in pK _a when pK _a 4.     

The depressing effect of tetracaine and ryanodine on the slow outward current correlated with that of contraction in voltage-clamped frog muscle fibres

The effects of tetracaine (10–50 M) and ryanodine (0.1–10 M) were tested on the slow outward K⁺ current (I _so) and the mechanical tension of isolated frog muscle fibres in a voltage-clamp device (double mannitol-gap) connected to a mechanoelectric transducer. In the concentration range tested, both drugs induced a simultaneous inhibition of tension and current. In all cases the effect on tension was twice that on current. The tetracaine-induced current and tension blocks were fully reversible and dose-dependent. In contrast the ryanodine effects on current and tension were not reversible and did not exhibit a dose dependence except for the delay before the onset of the response, which was shortened when the concentration was raised. Linear regression analysis of the time-dependent and dose-dependent effects of both drugs indicated a strong correlation between the decreases in tension and current. It is concluded that the slow outward current is partly under the control of the Ca²⁺ release from sarcoplasmic reticulum during contraction.