Miniature scintillating detector for small field radiation therapy

In planning stereotactic radiosurgery treatments, depth dose curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral electronic equilibrium and volume averaging. A scintillating detector with high spatial resolution and good reliability has been developed to overcome this problem. The miniature dosimeter consists of two identical radiation-resistant 10 m long silica optical fibers, each connected to an independent silicon photodiode. A small cylindrical polystyrene scintillator (3.9 mm3) is optically glued to the detection fiber. The light seen by the photodiode connected to this fiber arises from fluorescence of the scintillator and from the Cerenkov effect produced in silica. The reference signal produced by the fiber without scintillator is used to subtract the Cerenkov light contribution from the raw detector response. The sensitive volume of the scintillating detector is nearly water-equivalent and thus minimizes dose distribution perturbation in water. The miniature dosimeter has a spatial resolution comparable to the film-densitometer system. Profiles of 1 cm diam, 6 MV photon beam measured with both systems show very similar shapes. Furthermore, the use of photodiodes instead of photomultiplier tubes gives a better stability response and offers the possibility to perform absolute dosimetry.     

Is there still a place for angiography in the management of renal mass lesions?

In recent years, the development of noninvasive imaging modalities for exploration of the kidney has markedly reduced the use of angiography in the evaluation of renal masses. Presently, it is not required in routine practice to evaluate renal masses. Ultrasound is the most efficient procedure in detecting renal tumor. It is acknowledged that arteriography has a limited diagnostic and staging value compared with CT and MRI for the assessment of renal cell carcinomas (RCC). Most urologists recommend partial nephrectomy or tumor enucleation in an effort to preserve as much as possible functioning renal tissue. In such cases a preoperative map of the renal vasculature is not needed. Information on the main renal artery(ies) and segmental renal arteries can be provided with spiral CT or dynamic MR angiography. Arteriography remains useful in exceptional situations. Interventional arteriography is becoming an important part. It is indicated by means of selective embolization for the treatment of potentially bleeding tumor (i. e. angiomyolipoma) or in emergency in cases of acute hemorrhage. Less frequently, it may be proposed as a palliative procedure for inoperable patients with huge renal tumor. Two other indications of interventional arteriography are acknowledged. Some urologists request preoperative embolization of the tumor-harboring kidney to decrease/avoid extensive blood loss during surgery and/or to facilitate surgery with huge renal tumors when the renal vessels are difficult to reach. The complications of nephron-sparing surgery (partial nephrectomy or tumor enucleation) related to bleeding or arteriovenous fistulas may be cured by arterial embolization. Received: 18 May 1998; Revision received: 3 August 1998; Accepted: 6 August 1998     

Differential response of fast hindlimb extensor and flexor muscles to exercise in adult spinalized cats

Adult cats were spinal transected (T12-13) and maintained for approximately 6 months. Spinal cats were either not trained (N-T) or trained for 30 min/day to either step on a treadmill (Stp-T) or stand (Std-T). Spinalization resulted in a decrease in the mass and maximum tension potential of the medial gastrocnemius (MG), a fast ankle extensor. These adaptations were ameliorated in Std-T but not Stp-T cats. The maximum rate of shortening was elevated by 18 (ns), 34, and 19 (ns)% in the N-T, Std-T, and Stp-T cats, respectively, a finding consistent with a shift in the percentage of fast fibers, a decrease in the percentage of fibers expressing only type I myosin heavy chain, and an increase in myofibrillar adenosine triphosphatase activity. The shift toward a faster fiber type profile in the tibialis anterior (TA), a fast ankle flexor, was of a lesser magnitude than in the MG. There were no significant effects on the contractile properties of the TA in any group of spinal cats. The greater preservation of muscle mass, shift toward faster physiological and biochemical properties, and fatigability in the MG of Std-T than Stp-T cats suggest that factors other than the level of activation and force generation must play a role in muscle homeostasis. From a clinical perspective, the results indicate that muscles innervated by motor neurons below the level of a complete spinal cord lesion are affected differentially by specific neuromuscular activity patterns.     

Control of smooth muscle cell proliferation--the role of the basement membrane

In atherogenesis and in response to vessel injury, arterial smooth muscle cells (SMCs) are activated from a quiescent, differentiated state into an actively proliferating and synthetic phenotype which migrate into the intima where the cells participate in the formation of a fibrous plaque or intimal hyperplasia. The mechanisms involved in the control of SMC function are not clear and no preventive therapy against SMC activation is available. Interactions between SMCs and the extracellular matrix have been shown to influence SMC structure and function through integrin-mediated signaling processes. The SMC basement membrane is a specific form of extracellular matrix which seems to be crucial for the maintenance of SMC quiescence and the disruption of these interactions is part of cellular activation after atherogenic or traumatic stimuli. This concept of "negative growth control" may constitute a future target for the development of new strategies in the prevention of SMC activation in atherogenesis and restenosis formation.     

Endovascular treatment of hemifacial spasm associated with a cerebral arteriovenous malformation using transvenous embolization: case report

OBJECTIVE AND IMPORTANCE: To illustrate that decompression of the facial nerve by transvenous endovascular treatment may relieve hemifacial spasm (HFS) caused by dilated veins. CLINICAL PRESENTATION: A 35-year-old man suffered severe chronic right HFS associated with a dilated right lateral mesencephalic vein lying in the vicinity of the facial nerve. This nonessential vein was recruited as a secondary collateral drainage from an inoperable left temporo-occipital arteriovenous malformation. INTERVENTION: The lateral mesencephalic vein was reached through the superior petrosal sinus using a transfemoral venous approach and was occluded with interlocking detachable coils (Target Therapeutics, Freemont, CA). There was complete remission of HFS without recurrence after 2.5 years of follow-up. CONCLUSION: This case report supports vascular compression in the pathogenesis of HFS and suggests that facial nerve injury is not essential for the therapeutic effect of surgical decompression.     

Ondansetron is more effective than metoclopramide for the treatment of opioid-induced emesis in post-surgical adult patients. Ondansetron OIE Post-Surgical Study Group

Nausea and vomiting are common side effects of opioids administered for pain control. This double-blind, randomized, parallel-group study evaluated the anti-emetic efficacy and tolerability of single intravenous (i.v.) doses of ondansetron 8 mg, ondansetron 16 mg and metoclopramide 10 mg in the treatment of opioid-induced emesis. Adult patients undergoing low emetogenic surgical procedures, using a standardized anaesthesia regimen were assessed for 24 h following administration of study anti-emetic to treat established post-surgical opioid-induced emesis. A total of 4511 patients were enrolled of whom 1366 experienced opioid-induced emesis and received randomized study medication. Ondansetron 8 mg and 16 mg were significantly better than metoclopramide 10 mg (P < 0.05) for both complete control of emesis, complete control of nausea and other efficacy measures. There were no significant differences between the two ondansetron groups. All three treatments were well tolerated. In conclusion, this large, multicentre study demonstrates that ondansetron is more effective than metoclopramide in the treatment of opioid-induced emesis following administration of post-surgical opioids to control pain.     

Evidence of linkage in subtypes of alcoholism

We believed that subtyping alcoholism might be an efficient strategy for mapping susceptibility genes. Cluster analysis is one of the possible statistical techniques for such a purpose. We required that, ideally, the variables to be used in cluster analysis should be: 1) related to alcoholism, 2) related to the severity of alcoholism, and 3) familial, i.e., correlated within families. Only three variables met all three conditions. Those included age of onset of ALDX1, smoking, and TPQ-HA. A global score of symptoms of alcoholism was systematically introduced as one of the variables composing a subset for cluster analysis, although this score did not show any familial aggregation. Our strategy led to a strong evidence of linkage at D15S230 in only 20 families whose members are mainly characterized by heavy smoking.     

The use of the iSTAT portable analyzer in patients undergoing cardiopulmonary bypass

Objective. To evaluate the utility of the iSTAT blood analyzer, a bedside device for hematocrit, sodium, potassium, and glucose measurement during cardiopulmonary bypass (CPB).Methods. Forty patients scheduled for elective CPB were evaluated prospectively. In addition to using the iSTAT analyzer, blood samples were analyzed at four time points: following induction of anesthetic, 10 min. after initiation of CPB, 60 min. after initiation of CPB, and following heparin neutralization by protamine. Blood glucose concentration was measured by the hospital laboratory using a Kodak Analyzer and by a glucose meter, electrolytes were evaluated by the Kodak Analyzer and BGE (a device which is commonly used for satellite laboratory determinations of electrolyte and blood gas results), and hematocrit samples were measured by the hospital laboratory using an NE 8,000 and a centrifuge. The means and standard deviations of the differences between the methods were calculated.Results. The hematocrit values determined by the iSTAT machine, when adjusted for the level of total protein (according to manufacturer's directions), differed from the laboratory values by 0.53 = 1.46 percentage points. An alternative to measuring total protein and making the adjustment is simply adding 1 % to the hematocrit in the pre-CPB period and 3% on-CPB or post-CPB, which we found to yield values that differed from the laboratory by 0.52 ± 1.42 percentage points. For all four tests (hematocrit, sodium, potassium, and glucose) the iSTAT had a similar relationship to the laboratory values as did the other commonly used means (centrifuge, BGE, and glucose meter) of clinical evaluation.Conclusion. In summary, we found that in patients undergoing CPB, the iSTAT values agreed sufficiently well with standard laboratory values and that the iSTAT instrument can be relied upon for bedside measurements.Presented in part at the Annual Meeting of the Society of Cardiovascular Anesthesiologists, Philadelphia, PA, May 1995, and at the 70th meeting of the IARS, Washington DC, March 1996. Supported in part by a grant by iSTAT Corporation.     

Capillary haemangioma

A 16-year-old boy presented with a hyperpigmented, velvety, not compressible, plaque on the medial side of right leg just below the knee for the last 10 years. Biopsy report revealed the lesion was nothing but capillary haemangioma. The case is presented here due to unusual presentation with a tendency to persist.