Radiotherapy for stages I and IIA/B testicular seminoma

Radiotherapy is generally accepted as a standard treatment for early-stage testicular seminoma. Relapse rates of 2% to 5% in clinical stage I and 10% to 20% in stage IIA/B (according to the Royal Marsden classification) can be achieved. Disease-specific survival reaches 100%. With such excellent cure rates, treatment-related side effects gain particular importance. Therefore, a prospective multicenter trial was initiated for radiotherapy of testicular seminoma with limited treatment portals and low total doses of irradiation. In clinical stage I, 483 patients were treated with 26 Gy to the para-aortic region only. In stage IIA, 42 patients and, in stage IIB, 18 patients received irradiation to the para-aortic and high iliac lymph nodes with 30 and 36 Gy, respectively. With a median time to follow-up of 55 months for stage I and 55.5 months for stage IIA/B, there were 18 (3.7%) and 4 (6.7%) cases of relapse in both treatment groups. Disease-specific survival was 99.6% in stage I and 100% in stage IIA/B. Acute toxicity was dominated by moderate gastro-intestinal side effects. No major late toxicity has been observed to date. Limited volume pure para-aortic treatment for stage I and para-aortic/high iliac irradiation for stage IIA/B with 26, 30 and 36 Gy, respectively, yields excellent cure rates with only moderate acute toxicity and is therefore recommended as standard treatment.

Aminoglycoside-RNA interactions

The structural and physico-chemical parameters promoting the binding of aminoglycosides to RNAs are becoming clear. The strength of the interaction is dominated by electrostatics, with the positively charged aminoglycosides displacing metal ions. Although aminoglycosides inhibit most known ribozymes, aminoglycosides or polyamines are able to catalyze specific RNA cleavage in the absence of metal ions.

Continuous intravenous midazolam infusion for Centruroides exilicauda scorpion envenomation

STUDY OBJECTIVE

We sought to describe the effects of continuous intravenous midazolam infusion as therapy for severe bark scorpion (Centruroides exilicauda) envenomation.

METHODS

A retrospective chart review from July 1, 1993, through January 1, 1998, identified all patients treated at a university hospital with International Classification of Diseases, Ninth Revision, codes 989.5 (toxic effect of venom) or E905.2 (scorpion sting causing poisoning). By using standardized collection forms, data were extracted from the medical record of every patient who had a grade III or IV envenomation and was treated with a continuous intravenous midazolam infusion.

RESULTS

Our search identified 104 patients; 34 had grade III or IV envenomation. Of these, 33 were treated in the ICU with continuous intravenous midazolam infusion. Median patient age was 4 years (range, 1 to 68 years). Midazolam dosage was adjusted to induce a light sleep state to control agitation and involuntary motor activity. The median amount of midazolam resulting in the first recorded decrease in agitation and involuntary motor activity was 0.30 mg/kg (range, 0.03 to 1.76 mg/kg). This first evidence of clinical improvement was recorded as 1.00 hour (median), with a range of 0.00 to 3.75 hours. The initial midazolam infusion rate was 0.10 mg x kg(-1) x h(-1) (median), with a range of 0.01 to 0.31 mg x kg(-1) x h(-1). The maximal midazolam infusion rate was 0.30 mg x kg(-1) x h(-1) (median), with a range of 0.06 to 1.29 mg x kg(-1) x h(-1). The median time until the maximal midazolam infusion rate was 2.5 hours (range, 0.00 to 8.50 hours). The median duration of infusion was 9. 50 hours (range, 4.25 to 20.50 hours). The median length of stay in the ICU was 15.17 hours (range, 6.0 to 28.0 hours), and 85% of patients were discharged directly home. All patients had resolution of abnormal motor activity and agitation during their midazolam infusion. Transient hypoxemia without evidence of end-organ dysfunction was documented in 4 patients during midazolam therapy.

CONCLUSION

A continuous intravenous midazolam infusion can be a safe, effective, and readily available treatment option for patients with grade III or IV C exilicauda envenomation.

Recurrent and persistent coagulopathy following pit viper envenomation

BACKGROUND

Coagulation abnormalities following crotaline (pit viper) snakebite have traditionally been considered short-lived, but laboratory studies have rarely been reported beyond the first few days of treatment for envenomation. During the course of an antivenom clinical trial, we observed coagulation defects as late as 2 weeks following envenomation.

OBJECTIVES

To document and characterize the recurrence or persistence of coagulopathy among patients envenomed by pit vipers and treated with a Fab antivenom.

METHODS

Patients with moderate pit viper envenomation were enrolled in a multicenter, prospective clinical trial. A Fab-based antivenom preparation, antivenom polyvalent crotalid (ovine) Fab, was administered in all cases. Platelet count, fibrinogen level, presence of fibrin split products, prothrombin time, and partial thromboplastin time were determined before treatment and at standard intervals during the following 2 weeks.

RESULTS

Of 38 patients completing the study, 20 (53%) had recurrent, persistent, or late coagulopathy 2 to 14 days after envenomation. Thrombocytopenia occurred in patients with prior thrombocytopenia; hypofibrinogenemia occurred only in those with prior hypofibrinogenemia or positive fibrin split products. No patient experienced significant spontaneous bleeding. One patient with coagulopathy developed minor bleeding following minor surgery 12 days after envenomation.

CONCLUSIONS

Prolonged or recurrent coagulopathy may occur after envenomation by North American pit vipers. Patients treated with Fab-based antivenom may benefit from periodic rather than single-bolus dosing. Patients with coagulopathy should undergo close monitoring during the first 2 weeks after snakebite.

Envenomations

Envenomations are uncommon, challenging causes of critical care admissions. This article describes the diagnosis and treatment of envenomations that cause the most critical care admissions in the United States. Most are caused by the following animals: rattlesnakes, copperheads, cottonmouths, coral snakes, brown recluse spiders, and bark scorpions.

Decay of the GRB 990123 optical afterglow: implications for the fireball model

Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 started approximately 8.5 hours after the event and continued until 18 February 1999. When combined with other data, in particular from the Robotic Telescope and Transient Source Experiment (ROTSE) and the Hubble Space Telescope (HST), evidence emerges for a smoothly declining light curve, suggesting some color dependence that could be related to a cooling break passing the ultraviolet-optical band at about 1 day after the high-energy event. The steeper decline rate seen after 1.5 to 2 days may be evidence for a collimated jet pointing toward the observer.

Folding of the four-way RNA junction of the hairpin ribozyme

The hairpin ribozyme consists of two loop-carrying duplexes (called A and B) that are adjacent arms of a four-way junction in its natural context in the viral RNA. We have shown previously that the activity of the ribozyme is strongly influenced by the structure adopted by the junction. In this study, we have used fluorescence resonance energy transfer to analyze the conformation and folding of the isolated four-way junction. Like other four-way RNA junctions, in the absence of added metal ions this junction adopts a square configuration of coaxially stacked arms, based on A on D and B on C stacking. Upon addition of magnesium ions, the junction undergoes an ion-induced transition to an antiparallel conformation. The data are consistent with folding induced by the binding of a single ion, with an apparent association constant in the range of 2000 M-1. Other divalent metal ions (calcium or manganese) can also induce this change in structure; however, sodium ions are unable to substitute for these ions, and are slightly inhibitory with respect to the transition. The loop-free hairpin junction adopts the same stacking conformer as the full ribozyme, but forms a more symmetrical X-shaped structure. In addition, the apparent stoichiometry of structural ion binding is lower for the isolated junction, and the affinity is considerably lower.

Structure and activity of the hairpin ribozyme in its natural junction conformation: effect of metal ions

The natural form of the hairpin ribozyme consists of a four-way RNA junction of which the single-stranded loop-carrying helices are adjacent arms. The junction can be regarded as providing a framework for constructing the active ribozyme, and the rate of cleavage can be modulated by changing the conformation of the junction. We find that the junction-based form of the hairpin ribozyme is active in magnesium, calcium, or strontium ions, but not in manganese, cadmium, or sodium ions. Using fluorescence resonance energy transfer experiments, we have investigated the global structure of the ribozyme. The basic folding of the construct is based on pairwise helical stacking, so that the two loop-carrying arms are located on opposite stacked helical pairs. In the presence of magnesium, calcium, or strontium ions, the junction of the ribozyme undergoes a rotation into a distorted antiparallel geometry, creating close physical contact between the two loops. Manganese ions induce the same global folding, but no catalytic activity; this change in global conformation is therefore necessary but not sufficient for catalytic activity. Fitting the dependence of the conformation on ionic concentration to a two-state model suggests that cooperative binding of two ions is required to bring about the folding. However, further ion binding is required for cleavage activity. Cobalt hexammine ions also bring about global folding, while spermidine generates a more symmetrical form of the antiparallel structure. Cadmium ions generate a different folded form, interpreted in terms of close loop-loop association while the junction is unfolded. Sodium ions were unable to induce any folding of the ribozyme, which remained slightly parallel. These results are consistent with a folding process induced by the binding of two group IIA metal ions, distributed between the junction and the loop interface.

Intravascular hemolysis associated with North American crotalid envenomation

CASE REPORT

This is a case of severe intravascular hemolysis, without significant coagulopathy, following envenomation by a North American crotalid. A MEDLINE search from 1966-1997, and a review of older literature, revealed no similar cases. A 4-year-old girl was envenomated in her right foot by a 2.5 foot-long rattlesnake whose description matched that of the Hopi rattlesnake (Crotalus viridis nuntius). The snake was not captured. Her initial hematocrit was 45%. In spite of treatment with antivenin and improvement in her lower extremity pain and swelling, her hematocrit decreased to 20.4%. Laboratory tests and clinical exam showed a Coombs positive hemolytic anemia without significant signs of coagulopathy.

[Comparative value of MR-angiography, helical CT and digital angiography in the preoperative assessment of abdominal aortic aneurysms]

PURPOSE

To compare helical CT with MR angiography in pre-operative assessment of abdominal aortic aneurysm (AAA).

MATERIAL AND METHODS

Twenty patients with AAA underwent helical-CT, MR-angiography and digital angiography. All exams were interpreted independently by two groups of observers. Kappa and rho were calculated to assess correlations. Sensitivity and specificity were calculated to compare each method with the "gold standard" digital angiography.

RESULTS

Inter-observer correlation was excellent. There was a very good agreement between both methods in the assessment of the maximal diameter and the proximal neck of the aneurysm. There was no significant difference in the assessment of stenoses of the visceral and iliac arteries, the number of renal arteries, and iliac extension.

CONCLUSION

Helical CT and MR angiography are equivalent in pre-operative assessment of AAA.

Global structure of four-way RNA junctions studied using fluorescence resonance energy transfer

Four-way helical junctions are found widely in natural RNA species. In this study, we have studied the conformation of two junctions by fluorescence resonance energy transfer. We show that the junctions are folded by pairwise coaxial helical stacking, forming one predominant stacking conformer in both examples studied. At low magnesium ion concentrations, the helical axes of both junctions are approximately perpendicular. One junction undergoes a rotation into a distorted antiparallel structure induced by the binding of a single magnesium ion. By contrast, the axes of the four-way junction of the U1 snRNA remain approximately perpendicular under all conditions examined, and we have determined the stacking conformer adopted.

Folding of the hairpin ribozyme in its natural conformation achieves close physical proximity of the loops

The hairpin ribozyme is a self-cleaving motif found in the negatives strand of the satellite RNA of some plant viruses. In its natural context, the ribozyme comprises four helices, two of which contain conserved formally unpaired loops, that are adjacent arms of a four-way RNA junction. We show that the arms that would carry these loops are brought close together in the global conformation of the isolated junction. Using fluorescence resonance energy transfer, we demonstrate a two-magnesium ion-dependent conformational transition of the complete ribozyme that brings the loopbearing arms into close physical proximity. The ribozyme is active as a four-way junction, and the rate of cleavage may be modulated by the conformation of the four-way junction.

Squamous cells as predictors of bacterial contamination in urine samples

STUDY OBJECTIVE

To determine whether squamous cells in urine indicate bacterial contamination.

METHODS

We prospectively studied 105 consecutive women who presented to the emergency department with symptoms suggestive of a urinary tract infection. Two urine samples were collected from each woman, a midstream clean-catch (MSCC) sample and a catheterized (CATH) sample. Microscopic urinalyses to assess for squamous cells and urine cultures to assess for bacterial contamination were performed on all samples. Bacterial contamination was defined as growth of fewer than 10,000 colonies of a single species per milliliter or growth of three or more species of commensal bacteria (mixed flora) in a urine sample.

RESULTS

Squamous cells were found in 99 of 105 CATH samples (94%); however, no CATH samples had bacterial contamination. Squamous cells were found in 101 of 105 MSCC samples (96%); however, only 22 MSCC samples (21%) had bacterial contamination.

CONCLUSION

The presence of squamous cells in CATH urine samples obtained from women is not indicative of bacterial contamination. The presence of squamous cells in MSCC urine samples obtained from women also is not a good indicator, with an overall predictive value for bacterial contamination of 21%.

Spinal cord injury with a narrow spinal canal: utilizing Torg's ratio method of analyzing cervical spine radiographs

A 65-year-old inebriated man crashed his car and presented with spinal shock and neurogenic shock from a cervical spinal cord injury without cervical spine fracture or dislocation. The lateral cervical spine radiography was initially read as normal, except for degenerative disk disease; however, Torg's ratio method of analyzing cervical spinal canal sagittal width indicated the spinal canal was congenitally narrow. Magnetic resonance imaging confirmed this and showed bulging and herniation of multiple invertebral disks between C2 and C7. This case illustrates the value of using Torg's ratio method of analyzing lateral cervical spine radiographs. Although Torg's method has not been prospectively validated, it may be useful to identify patients at risk for cervical spinal cord injuries without fractures or dislocations. An abnormal Torg's ratio may be the only clue to the fact that the patient is at higher risk of spinal cord injury when the patient's history or examination is questionable because of head injury, drug intoxication, or therapeutic sedation and paralysis.

Ion-induced folding of the hammerhead ribozyme: a fluorescence resonance energy transfer study

The ion-induced folding transitions of the hammerhead ribozyme have been analysed by fluorescence resonance energy transfer. The hammerhead ribozyme may be regarded as a special example of a three-way RNA junction, the global structure of which has been studied by comparing the distances (as energy transfer efficiencies) between the ends of pairs of labelled arms for the three possible end-to-end vectors as a function of magnesium ion concentration. The data support two sequential ion-dependent transitions, which can be interpreted in the light of the crystal structures of the hammerhead ribozyme. The first transition corresponds to the formation of a coaxial stacking between helices II and III; the data can be fully explained by a model in which the transition is induced by a single magnesium ion which binds with an apparent association constant of 8000-10 000 M-1. The second structural transition corresponds to the formation of the catalytic domain of the ribozyme, induced by a single magnesium ion with an apparent association constant of approximately 1100 M-1. The hammerhead ribozyme provides a well-defined example of ion-dependent folding in RNA.

Exotic snakebite: envenomation by an African puff adder (Bitis arietans)

We report an envenomation by the African puff adder (Bitis arietans), an exotic snake in the United States. The patient developed swelling and ecchymoses in the affected extremity, and cutaneous necrosis of the envenomated fingertip. There was no significant coagulopathy. He received 20 vials of specific antivenin (Schlangengift-Immunserum Behring Zentralafrika, Behringwerke, Marburg, Germany) and debridement of devitalized finger tissue. The only permanent sequelae were cutaneous scarring and permanent loss of the fingernail on the envenomated finger. Exotic snakebite is a rare presenting problem in emergency departments. The initial approach to a patient envenomated by an exotic venomous snake is discussed. Use of antivenin and supportive care are emphasized.

Loxosceles arizonica bite associated with shock

Envenomation by the brown recluse spider (Loxosceles reclusa) is associated with shock, significant hemolysis, renal insufficiency, and disseminated intravascular coagulation (DIC). Shock has never been associated with envenomation by L arizonica, a related species indigenous to Arizona, southern California, and northwestern Mexico. We report the case of a 13-year-old girl, bitten by a specimen of L arizonica (the spider was identified by an entomologist), in whom shock and a typical cutaneous lesion developed. She did not experience renal insufficiency or disseminated intravascular coagulation. Infectious causes of shock were excluded. She recovered completely with supportive care.

Snakes and snakebite in Central America

This review treats the general biology, taxonomy, distribution and venom apparatus of the venomous snakes of Central America. Consideration has been given to the chemistry, pharmacology and immunology of the venom, and particular attention is dispensed to the clinical problem, including the treatment, of envenomations by these reptiles.

Modulation of ovarian function by an oral contraceptive containing 30 micrograms ethinyl estradiol in combination with 2.00 mg dienogest

Twenty-two healthy female volunteers with normal ovulatory cycles, aged between 20 and 34 years (27.3 +/- 4.1), were included in a single-center, noncomparative study to investigate the modulation of ovarian function by an oral contraceptive containing 30 micrograms ethinyl estradiol in combination with 2.00 mg dienogest. At baseline, during three treatment cycles and post-treatment, serum levels of luteinizing hormone, follicle-stimulating hormone, 17 beta-estradiol, and progesterone were assayed and ultrasonography was used to measure follicular size and the thickness of the endometrium. The primary efficacy variable was inhibition of ovulation as measured by ovarian activity grading. All volunteers ovulated during the pretreatment cycle. During treatment, none of the subjects had ovulatory cycles, although there was still some ovarian activity in several subjects. During the first treatment cycle, only 4% (1 subject) of cycles showed active follicle-like structures. The frequency of follicle-like structures increased to 33% and 35% during treatment cycles 2 and 3. The frequency of presumptive luteinized unruptured follicle-like structures was 5% (1 subject) and 15% (3 subjects) in treatment cycles 2 and 3. The serum hormone concentrations were effectively suppressed in comparison to baseline. The ovarian activity returned to baseline during the post-treatment period. One subject was excluded from further study because of a medical problem believed unrelated to use of the oral contraceptive. No serious adverse events were recorded during the course of the study. The results of the present investigation indicate that the modulatory effects on ovarian function of the monophasic oral-contraceptive containing 30 micrograms ethinyl estradiol combined with 2.00 mg dienogest lead to adequate suppression of ovarian activity and effective inhibition of ovulation.

Cisapride poisoning

A MEDLINE search from 1966-1996 revealed no reports of cisapride poisoning. An 8-mo-old, 8.9 kg girl received 8 mL of cisapride (Propulsid Suspension, 1 mg/mL, Janssen Pharmaceutica, Titusville, NJ) rather than the usual dose of 0.8 mL, resulting in an inadvertent, 10-fold, iatrogenic, dosing error. She developed emesis, hyperactive bowel sounds, abnormal behavior, mild hyperthermia, tachycardia, hypertension, and thrombocytosis. This is the first published report of poisoning with cisapride.

Double-blind, randomized, placebo controlled study on the effects of the monophasic oral contraceptive containing 30 micrograms ethinyl estradiol and 2.00 mg dienogest on the hemostatic system

Forty healthy female volunteers aged between 19 and 35 years (27.3 +/- 4.1 years) with normal menstrual cycles were included in a double-blind, randomized, placebo-controlled study to investigate the influence on the hemostatic system of an oral contraceptive containing 30 micrograms ethinyl estradiol in combination with 2.00 mg dienogest, which is a 19-norprogestin without a 17 alpha-ethinyl group. At baseline and during one treatment cycle, 12 hemostatic parameters were measured on cycle days 7, 14, and 21. The hemostatic parameters were categorized as either procoagulatory, anticoagulatory and profibrinolytic, or antifibrinolytic and indicative of fibrin turnover. Differences between placebo and 30 micrograms ethinyl estradiol and 2.00 mg dienogest of plasma levels of hemostatic parameters on cycle days 21 of the precycle and treatment cycle were chosen as target variables. Prothrombin fragment 1 + 2 (F 1 + 2) was chosen as the main target variable. Equivalence of F 1 + 2 between placebo and active treatment was noted. Among the procoagulatory factors, only factor VII activity was found to be increased over placebo in the active treatment group, but decreased in the placebo group. Protein C activity increased during the treatment with 30 micrograms ethinyl estradiol and 2.00 mg dienogest, and was higher than that of the placebo group in which this parameter decreased during the treatment cycle. There was a corresponding increase in fibrinolytic activity being reflected by higher plasminogen levels in the active treatment group in comparison with placebo. An increase was noted for the fibrinolytic parameter D-dimer. Apart from isolated measurements, the parameters remained in their respective normal ranges. The data combine to suggest that 30 micrograms ethinyl estradiol and 2.00 mg dienogest has a balanced effect on the hemostatic system stimulating both procoagulatory and fibrinolytic activity.