Oral Microbiota Composition Predicts Early Childhood Caries Onset

As the most common chronic disease in preschool children in the United States, early childhood caries (ECC) has a profound impact on a child's quality of life, represents a tremendous human and economic burden to society, and disproportionately affects those living in poverty. Caries risk assessment (CRA) is a critical component of ECC management, yet the accuracy, consistency, reproducibility, and longitudinal validation of the available risk assessment techniques are lacking. Molecular and microbial biomarkers represent a potential source for accurate and reliable dental caries risk and onset. Next-generation nucleotide-sequencing technology has made it feasible to profile the composition of the oral microbiota. In the present study, 16S ribosomal RNA (rRNA) gene sequencing was applied to saliva samples that were collected at 6-mo intervals for 24 mo from a subset of 56 initially caries-free children from an ongoing cohort of 189 children, aged 1 to 3 y, over the 2-y study period; 36 children developed ECC and 20 remained caries free. Analyses from machine learning models of microbiota composition, across the study period, distinguished between affected and nonaffected groups at the time of their initial study visits with an area under the receiver operating characteristic curve (AUC) of 0.71 and discriminated ECC-converted from healthy controls at the visit immediately preceding ECC diagnosis with an AUC of 0.89, as assessed by nested cross-validation. Rothia mucilaginosa, Streptococcus sp., and Veillonella parvula were selected as important discriminatory features in all models and represent biomarkers of risk for ECC onset. These findings indicate that oral microbiota as profiled by high-throughput 16S rRNA gene sequencing is predictive of ECC onset.

The impact of fatigue on the non-technical skills performance of critical care air ambulance clinicians

BACKGROUND

The relationship between fatigue-related risk and impaired clinical performance is not entirely clear. Non-technical factors represent an important component of clinical performance and may be sensitive to the effects of fatigue. The hypothesis was that the sum score of overall non-technical performance is degraded by fatigue.

METHODS

Nineteen physicians undertook two different simulated air ambulance missions, once when rested, and once when fatigued (randomised crossover design). Trained assessors blinded to participants' fatigue status performed detailed structured assessments based on expected behaviours in four non-technical skills domains: teamwork, situational awareness, task management, and decision making. Participants also provided self-ratings of their performance. The primary endpoint was the sum score of overall non-technical performance.

RESULTS

The main finding, the overall non-technical skills performance rating of the clinicians, was better in rested than fatigued states (mean difference with 95% CI, 2.8 [2.2-3.4]). The findings remained consistent across individual non-technical skills domains; also when controlling for an order effect and examining the impact of a number of possible covariates. There was no difference in self-ratings of clinical performance between rested and fatigued states.

CONCLUSION

Non-technical performance of critical care air transfer clinicians is degraded when they are fatigued. Fatigued clinicians may fail to recognise the degree to which their performance is compromised. These findings represent risk to clinical care quality and patient safety in the dynamic and isolated environment of air ambulance transfer.

Prenatal diagnosis of critical congenital heart disease reduces risk of death from cardiovascular compromise prior to planned neonatal cardiac surgery: a meta-analysis

OBJECTIVE

To determine if prenatal diagnosis improves the chance that a newborn with critical congenital heart disease will survive to undergo planned cardiac surgery.

METHODS

A systematic review of the medical literature identified eight studies which met the following criteria: compared outcomes between newborns with prenatal and those with postnatal diagnosis of critical congenital heart disease; compared groups of patients with the same anatomical diagnosis; provided detailed information on cardiac anatomy; included detailed information on preoperative cause of death. A meta-analysis was performed to assess differences in preoperative mortality rates between newborns with prenatal diagnosis and those with postnatal diagnosis. Patients with established risk factors for increased mortality (high risk) and those whose families chose comfort care rather than cardiac surgery were excluded.

RESULTS

In patients with comparable anatomy, standard risk, a parental desire to treat and optimal care, newborns with a prenatal diagnosis of critical congenital heart disease were significantly less likely to die prior to planned cardiac surgery than were those with a comparable postnatal diagnosis (pooled odds ratio, 0.26; 95% CI, 0.08-0.84).

CONCLUSIONS

For newborns most likely to benefit from treatment for their critical congenital heart disease, because they did not have additional risk factors and their families pursued treatment, prenatal diagnosis reduced the risk of death prior to planned cardiac surgery relative to patients with a comparable postnatal diagnosis. Further study and efforts to improve prenatal diagnosis of congenital heart disease should therefore be considered.

Echocardiographic findings in 11 cats with acromegaly

Background

Information regarding cardiac changes in domestic cats with acromegaly is limited.

Hypothesis/Objectives

The objective of this study was to describe the echocardiographic findings in cats with acromegaly.

Animals

Eighteen cats diagnosed with acromegaly at Colorado State University between 2008 and 2012. Of these 18 cats, 11 had echocardiography performed.

Methods

A retrospective review of medical records was made to identify cats with acromegaly that also had echocardiography performed.

Results

Of the 11 cats identified, 7 had left ventricular concentric hypertrophy, 6 had left atrial enlargement, and 7 had evidence of abnormal diastolic function. All 11 cats had evidence of structural or functional cardiac disease.

Conclusions and Clinical Importance

Cardiovascular abnormalities frequently are present in cats with acromegaly, and a complete cardiac evaluation should be considered in these patients.

Leflunomid reduziert den Angiogenesescore und das Tumorwachstum subkutan implantierter Kolonkarzinomzellen im Mausmodell

BACKGROUND

The inhibition of tumorangiogenesis may be of importance in the additive treatment of various cancers. Leflunomide, a drug which has been approved in Germany for the therapy of rheumatoid arthritis, inhibits the activity of several growth factors in vitro. The aim of this study was to investigate the effects of the drug on tumor angiogenesis in a nude mouse model.

MATERIALS AND METHODS

A total of 40 nude mice were injected with human colon carcinoma cells. Following randomization in 4 groups, therapy started on day five. Group 1 was treated daily with orally administered Leflunomide (35 mg/kg) dissolved in 1.5% Carboxymethylcellulose (CMC). Group 2 served as a control group and received 1 ml CMC orally per day. The animals of group 3 were treated daily with 35 mg Leflunomide/kg KG and 500 mg Uridine/kg dissolved in 1 ml Nacl 0.9% intraperitoneally. The 4th group again served as a control group and received only 500 mg Uridine/kg intraperitoneally each day. The main outcome criterion was the angiogenesis score (AS). In addition, the tumor volume and tumor weight were also assessed. The AS was determined by immunohistochemistry using an antibody against factor VIII related antigen.

RESULTS

All animals tolerated the procedure well. In the Leflunomide and the Leflunomide/Uridine group the angiogenesis score (p < 0.01), the tumor volume (p < 0.01) and the tumor weight (p < 0.01) were lower compared to the respective control groups.

CONCLUSION

The administration of Leflunomide leads to a significant reduction of tumor weight and tumor volume following subcutaneous injection of human colon carcinoma cells in a nude mouse model. This could be due to the reduction of tumor angiogenesis. Following further experimental and clinical studies, Leflunomide may come to play a role in the additive treatment of colonic carcinoma.

Simulations of the two-dimensional electronic spectroscopy of the photosystem II reaction center

We report simulations of the two-dimensional electronic spectroscopy of the Q(y) band of the D1-D2-Cyt b559 photosystem II reaction center at 77 K. We base the simulations on an existing Hamiltonian that was derived by simultaneous fitting to a wide range of linear spectroscopic measurements and described within modified Redfield theory. The model obtains reasonable agreement with most aspects of the two-dimensional spectra, including the overall peak shapes and excited state absorption features. It does not reproduce the rapid equilibration from high energy to low energy excitonic states evident by a strong cross-peak below the diagonal. We explore modifications to the model to incorporate new structural data and improve agreement with the two-dimensional spectra. We find that strengthening the system-bath coupling and lowering the degree of disorder significantly improves agreement with the cross-peak feature, while lessening agreement with the relative diagonal/antidiagonal width of the 2D spectra. We conclude that two-dimensional electronic spectroscopy provides a sensitive test of excitonic models of the photosystem II reaction center and discuss avenues for further refinement of such models.

The role of neutropenia on outcomes of cancer patients with community-acquired pneumonia

Although the presence of neutropenia may predispose cancer patients to develop community-acquired pneumonia, the role of neutropenia on their outcomes has not been investigated. The purpose of the present study was to compare clinical outcomes of cancer community-acquired pneumonia patients with and without neutropenia. Patients with cancer, identified in the Community-Acquired Pneumonia Organization database, were divided into two groups according to the type of cancer and the presence of neutropenia: patients with solid cancer without neutropenia versus those with functional or absolute neutropenia. Among the 3,106 community-acquired pneumonia patients enrolled, 135 had cancer without neutropenia and 75 had cancer with neutropenia. No significant difference was found between patients with and without neutropenia regarding mean time to clinical stability (5.4+/-2.7 versus 4.9+/-2.7 days, respectively), mean length of hospital stay (9.2+/-7.7 versus 9.9+/-9.6 days) and in-hospital mortality (18 versus 15%, respectively). Using a multiple logistic regression model, neutropenia was not associated with mortality in cancer patients when adjusting for significant covariates (odds ratio 1.30). Lack of neutropenia, during the initial evaluation of a cancer community-acquired pneumonia patient, should not be considered an indicator of better clinical outcome.

Laparoscopic ultrasound as the primary method for bile duct imaging during cholecystectomy

BACKGROUND

Intraoperative fluorocholangiography (IOC) has been the standard method for bile duct imaging during cholecystectomy. Laparoscopic ultrasound (LUS) has been evaluated as a possible alternative, but has been used less frequently. The authors examined the evolving use of these two methods to assess the relative utility of LUS as the primary method for routine bile duct imaging during laparoscopic cholecystectomy (LC).

METHODS

This study analyzed a prospective database containing 423 consecutive cholecystectomies performed by one attending surgeon in an academic medical center between 1995 and 2005.

RESULTS

Intraoperative bile duct imaging was performed in 371 (94%) of 396 LCs performed for cholelithiasis. As recorded, IOC was performed in 239 cases, LUS in 236 cases, and both in 104 cases. Choledocholithiasis was present in 50 patients (13%). Common bile duct stones (CBDS) were identified by LUS in 3% of the patients without preoperative indicators of CBDS, and in 10% of the patients with one or more indicators. As shown by the findings, LUS had a positive predictive value of 100%, a negative predictive value of 99.6%, a sensitivity of 92.3%, and a specificity of 100% for detecting CBDS. Also, LUS identified clinically significant bile duct anatomy in 6% of the patients. In 1995, LUS was used for 20% of cases, whereas by 2005, it was used for 97% of cases. Conversely, the use of IOC decreased from 93% to 23%.

CONCLUSIONS

With moderate experience, LUS can become the primary routine imaging method for evaluating the bile duct during LC. It is as reliable as IOC for detecting choledocholithiasis. In addition, LUS can locate the common bile duct during difficult dissections. On the basis of this experience, LUS is used currently in nearly all LCs and is the sole method for bile duct imaging in 75% of these cases. IOC is used as an adjunct to LUS when LUS imaging is inadequate, when stronger clinical indicators of choledocholithiasis are present, or when biliary anatomy remains uncertain.

A low-cost fiber-optic instrument to colorimetrically detect patients with Barrett's esophagus for early detection of esophageal adenocarcinoma

In Barrett's esophagus, the precursor to esophageal adenocarcinoma, the squamocolumnar junction (SCJ) between the normal esophagus and the stomach like mucosa is proximally displaced. Currently it can be detected only by an expensive upper GI endoscopic procedure. We have developed a minimally invasive and easy to operate colorimetric instrument for the low-cost detection of Barrett's esophagus. The instrument is based on a flexible, narrow diameter, fiber-optic probe that performs a colorimetric scan of the esophageal lumen. The instrument was clinically evaluated in 50 subjects. The instrument could identify both symmetric and asymmetric SCJ's. The SCJ locations determined by the colorimetric instrument correlated strongly (R2 = 0.89) with those determined by endoscopy. The instrument identified the SCJ locations accurately (Mean of difference +/- SEM: 0.97 +/- 1.72 cm) and reproducibly (Mean of absolute difference +/- SEM: 1.33 +/- 1.40 cm). The instrument has a 90% sensitivity of identifying patients with Barrett's esophagus, based on the clinical algorithm that if the SCJ is located at a distance less than 37 cm from the teeth, then the subject has Barrett's esophagus, otherwise the subject does not have Barrett's esophagus. In conclusion, the colorimetric instrument has the potential of being a cost-effective way of determining patients likely to have Barrett's esophagus in the population.

Do angiogenesis and growth factor expression predict prognosis of esophageal cancer?

A retrospective study of surgically resectable esophageal cancers was undertaken to determine the relationship between angiogenesis score and growth factor expression with tumor size, histology, degree of differentiation, depth of invasion, nodal disease, and the presence of Barrett's esophagus. The office and hospital charts of 27 patients who had esophageal resection for carcinoma between 1990 and 1995 at Rush-Presbyterian-St. Luke's Medical Center were reviewed. Data collection included patient demographics, survival, tumor size, histology, differentiation, depth of invasion, nodal metastases, and the presence of Barrett's esophagus. The pathology specimens were immunostained for von Willebrand factor (factor VIII-related antigen). Immunostaining was also performed for vascular endothelial growth factor and transforming growth factor alpha. Twenty normal esophageal specimens served as controls. Angiogenesis score was determined by counting vessels under conventional light microscopy at x200 magnification, and growth factor expression was graded on a scale of 1 to 4. Cancers had higher angiogenesis and growth factor expression than controls (P = 0.01). Patient age, tumor size, histology, differentiation, depth of invasion, and Barrett's esophagus did not correlate with angiogenesis score or tumor growth factor expression. Lymph node status did correlate with both angiogenesis score and growth factor expression (P < or = 0.02). We conclude that high angiogenesis score and growth factor expression correlate with the presence of lymph node metastases. This may help select patients for preoperative radiation and chemotherapy or determine the extent of surgery performed for esophageal carcinoma.

In vitro and in vivo antitumor activity of a novel immunomodulatory drug, leflunomide: mechanisms of action

Leflunomide, a novel immunomodulatory drug, has two biochemical activities: inhibition of tyrosine phosphorylation and inhibition of pyrimidine nucleotide synthesis. In the present study, we first showed that A77 1726 [N-(4-trifluoromethylphenyl-2-cyano-3-hydroxycrotoamide)], the active metabolite of leflunomide, was more effective at inhibiting the tyrosine kinase activity of platelet-derived growth factor (PDGF) receptor than that of epidermal growth factor (EGF) receptor, and had no effect on the tyrosine kinase activity of the fibroblast growth factor receptor. In the presence of exogenous uridine, A77 1726 was more effective at inhibiting the PDGF-stimulated proliferation of PDGF receptor-overexpressing C6 glioma than the EGF-stimulated proliferation of EGF receptor-overexpressing A431 cells. In vivo studies demonstrated that leflunomide treatment strongly inhibited the growth of the C6 glioma but had only a modest effect on the growth of the A431 tumor. Uridine co-administered with leflunomide did not reverse the antitumor activity of leflunomide on C6 and A431 tumors significantly. Quantitation of nucleotide levels in the tumor tissue revealed that leflunomide treatment significantly reduced pyrimidine nucleotide levels in the fast-growing C6 glioma but had no effect on the relatively slow-growing A431 tumor. Whereas uridine co-administration normalized pyrimidine nucleotide levels, it had minimal effects on the antitumor activity of leflunomide in both tumor models. Immunohistochemical analysis revealed that leflunomide treatment significantly reduced the number of proliferating cell nuclear antigen-positive cells in C6 glioma, and that uridine only partially reversed this inhibition. These results collectively suggest that the in vivo antitumor effect of leflunomide is largely independent of its inhibitory effect on pyrimidine nucleotide synthesis. The possibility that leflunomide exerts its antitumor activity by inhibition of tyrosine phosphorylation or by a yet unidentified mode of action is discussed.

[Rectal formalin instillation--a practical and reliable therapy of hemorrhagic proctitis]

Hemorrhagic proctitis is a rare, but severe complication of radiation therapy in the treatment of several pelvic malignancies. Administration of topical steroids, anti-inflammatory agents or laser therapy and rectal instillation of 4% formalin have been described as a method of treating this complication. A dog model was established to study the safest volume and duration of administration of formalin, the histological changes in the rectal mucosa, and rectal compliance following this treatment.

METHOD

Twenty-one mongrel dogs were assigned randomly to seven groups. Three dogs received a rectal formalin bolus of 400 ml for 1 h; in the other six groups formalin was instilled in 30 ml aliquots to a total volume of 400 ml. Serum levels of formalin were obtained at designated time intervals, rectal compliance was evaluated pre- and post-formalin instillation, and rectal mucosa was analyzed for blood-vessel density and mucosal injury at different time points.

RESULTS

Serum formalin in the bolus group reached toxic levels, while sequential instillation caused no serum toxicity in any dog. Rectal compliance and mucosal thickness were not affected by formalin, but there was a decrease in the angiogenesis score, and mild proctitis was seen in the acute and 1-week group.

Percutaneous penetration of Aldara cream, 5% during the topical treatment of genital and perianal warts

Objective: The objective of this single-center, open-label trial was to evaluate the percutaneous penetration of Aldara (imiquimod) cream, 5% when applied topically to patients with anogenital warts using a more frequent/aggressive dosing regimen.Methods: Ten otherwise healthy males and six otherwise healthy, nonpregnant, nonlactating females with histology results suggestive of, or diagnostic of, human papilloma virus/condyloma acuminata were enrolled. Females were required to be practicing an acceptable form of contraception control. Patients applied cream daily (8 +/- 2 hours) until complete wart clearance, or for a maximum of 16 weeks. Following the initial dose, at approximately week 4, and at the end-of-treatment, patients were confined for 42 hours in order to obtain a series of blood and urine samples. These samples were analyzed for levels of imiquimod and two metabolites, S-26704 and S-27700. Biological marker levels were not included as a part of this trial.Results: No quantifiable (>/=5 ng/mL) levels of imiquimod or the two metabolites were observed in any of the serum samples collected. Five patients had quantifiable (>/=10 ng/mL) imiquimod, S-26704, or both in urine. No quantifiable levels of S-27700 were observed. Complete clearance of warts occurred in 40% of male patients and 83% of female patients. Erythema was the most frequently observed local skin reaction and was moderate in intensity, although 6 of 16 patients reported a severe erythema reaction at some point in the study. Application site reactions (itching, burning and pain) were the most frequently reported adverse events.Conclusion: The lack of quantifiable levels of imiquimod or metabolites in serum, together with sporadically occurring quantifiable but low levels in urine, indicate that systemic exposure, after daily application of Aldara cream to genital/perianal skin, may occur but is minimal; however, pharmacological (immune marker) effects were not evaluated because cytokine measurements were not obtained. A future trial assessing cytokine levels after topical Aldara therapy with minimal systemic levels of imiquimod would help assess systemic drug and pharmacological effects and utility of this product in pregnant women.

Mechanical, histologic, and biochemical effects of canine rectal formalin instillation

Instillation of 4 percent formalin effectively treats radiation hemorrhagic proctitis; however, little is known regarding its side effects.

PURPOSE

The study contained herein was undertaken to determine rectal compliance and collagen content, mucosal and vascular histologic changes, and kinetics of formalin absorption following instillation.

METHODS

Fifteen mongrel dogs (50-60 pounds) were randomized into five experimental groups according to time elapsed from formalin treatment: control, acute, one week, two weeks, and four weeks. Formalin was instilled in 30-ml aliquots to a total volume of 400 ml. Rectal compliance (closed manometry system) was assessed pre-formalin and post-formalin at the designated time interval. Serum formalin metabolites were determined at time 0, 0.5, 1, and 3 hours. A segment of rectal wall was analyzed for collagen content, mucosal injury, and blood vessel density.

RESULTS

Serum formalin levels peaked within 30 minutes, returning to normal by 3 hours. With the exception of one dog, toxic levels were not reached at any time during the study. No dogs experienced sepsis, fever, or altered gastrointestinal function. Acute and one-week dogs showed mild diffuse proctitis and mucosal slough, which healed within two weeks. Rectal compliance and collagen content were unchanged. Mucosal blood vessels decreased in number early (P = 0.03).

CONCLUSIONS

Instillation of 4 percent formalin in sequential aliquots of a small volume that is kept in contact for a short period of time is safe. Serum formalin levels generally do not reach toxic levels, and the slight elevation in formalin concentration that was seen returns to normal within three hours. Formalin-induced proctitis heals within two weeks, and no long-term changes in rectal compliance or collagen content were seen.

Absorption kinetics of rectal formalin instillation

Formalin instillation has become an accepted treatment of radiation-induced hemorrhagic cystitis and proctitis since the initial report by Brown in 1969 (Med. J. Aust. 1:23, 1969). Although its use is widespread, no studies have been performed to determine the safest, volume or duration of formalin exposure. The purpose of our study was to determine the optimum technique for instillation and the safety margin regarding the maximum time that formalin can be in contact with the rectal mucosa without causing serum toxicity. In a pilot canine study, 4% neutral buffered formalin was instilled into the rectum in 30 ml aliquots for 60 seconds each after which each aliquot was withdrawn; a total volume of 400 ml was used. Our subsequent experiment involved rectal instillation of a single formalin bolus of 100 ml for 1 hour without removal during this time. Formalin metabolites were measured in the blood and urine to assess toxicity. Results indicate that with the latter technique serum formic acid reaches toxic levels within 15 minutes of instillation and may stay elevated for several hours. Metabolites in the urine similarly increase within 15 minutes, lagging only shortly behind the rise in serum levels. Performing formalin instillation in a series of 30 ml aliquots appears to be a safer treatment, as toxic serum levels were not reached and their slight rise above baseline returned to normal within 3 hours.

Minimum urine flow rate during water deprivation: importance of the nonurea versus total osmolality in the inner medulla

Antidiuretic hormone leads to an increase in the permeability for water and urea in the inner medullary collecting duct. Hence, urea may not be an "effective" osmole in the inner medulla during maximal renal water conservation. Accordingly, the purpose of this study was to evaluate whether differences in the rate of urea excretion would influence maximum renal water conservation in humans. In water-deprived rats, the concentration of urea and total osmolality were somewhat higher in the urine exiting the inner medullary collecting duct than in interstitial fluid obtained from the entire papillary tip. Nevertheless, the "nonurea" (total osmolality minus urea in millimolar terms) osmolality was virtually identical in both locations. Chronically fasted human subjects that were water-deprived for 16 h had a lower rate of urea excretion (71 +/- 7 versus 225 +/- 14 mumol/min) and a somewhat lower urine osmolality (745 +/- 53 versus 918 +/- 20 mosmol/kg H2O). Nevertheless, they had identical urine flow rates (0.5 +/- 0.01 and 0.5 +/- 0.02 ml/min, respectively), and their nonurea osmolality also was similar (587 +/- 25 and 475 +/- 14 mosmol/kg H2O, respectively) to the water-deprived normal subjects. The composition of their urine differed in that the principal nonurea osmoles became NH4+ and beta-hydroxybutyrate rather than Na and C1. During water deprivation in normal subjects, the ingestion of urea caused a twofold rise in urine flow rate, a fall in the nonurea osmolality, and a rise in the rate of excretion of nonurea osmoles. The nonurea osmolality of the urine, and presumably the medullary interstitial fluid as well, was inversely related to the urea excretion rate. In chronic fasting, the nature, but not the quantity, of nonurea osmoles changed. The similar minimum urine volume was predictable from an analysis based on nonurea osmole considerations.

Comparison of tests for detecting leaks in the low-pressure system of anesthesia gas machines

Small leaks in the low-pressure system (LPS) of the anesthesia gas machine can cause hypoxia or patient awareness. We sought to determine the relative sensitivities of the various tests recommended for detecting LPS leaks before anesthesia. Special adapters were fashioned to create leaks of six different sizes in the LPS that were equivalent to the following: a single 25-, 22-, 20-, or 15-gauge needle, two 15-gauge needles, or a 2.5-mm endotracheal tube connector. With each leak condition, five different leak tests were performed on three each of the following machines: Ohmeda Modulus I, Ohmeda Modulus II-Plus, and North American Dräger Narkomed (2A, 3 and 4), for a total of 54 leaks to be detected for each leak test (3 x 3 x 6). The number of leaks detected with each test was compared by Fisher's exact test, P < 0.05 being considered significant. Only the negative pressure leak test detected all 54 leaks, a significant difference from the positive pressure test, which detected the least number of leaks, 28 (P < 0.05). Some leak tests are more suitable for specific anesthesia machines. Adoption of the negative pressure test as a universal LPS leak test may prevent the risks associated with using the wrong test for the particular anesthesia machine: hypoxic gas or patient awareness.

An optical fiber transducer for single myofibril force measurement

A force transducer has been developed for use in force measurement of skeletal muscle myofibrils. The transducer is suitable for measurement of passive and contractile forces in a range up to 200 micrograms, with 1 microgram resolution. It is based upon the operating principle of the deflection of an optical fiber of known compliance, sensed by the differential illumination of two phototransistors. Attractive features include ease of operation and specimen mounting, high bandwidth, adaptability for different force ranges, and simple and inexpensive construction.

Molten globule monomer to condensed dimer: role of disulfide bonds in platelet factor-4 folding and subunit association

Platelet factor 4 (PF4) exhibits high affinity for heparin and exists as a tetramer in solution under physiologic conditions. Reduction of the two disulfide bridges in PF4 increases the protein's dissociation constant for heparin approximately 20-fold and shifts the highest apparent aggregation state from tetramer to dimer as evidenced by gel filtration, chemical cross-linking, and 1H-NMR studies. 1H-NMR spectra of reduced PF4 monomers generally show narrower, less dispersed, upfield-shifted NH and alpha H resonances, suggesting the presence of an unfolded monomer state. Reduced PF4 monomer folding, however, is evidenced by the presence of about 12 relatively long-lived backbone NHs and by CD spectra that indicate conservation of overall secondary structure. These data suggest the presence of a molten globule-type state. Urea denaturation shifts this apparent molten globule to a fully unfolded state characterized by more random coil-like resonance shifts. The reduced PF4 dimer state yields NMR and CD data consistent with preservation of tertiary structural folds found for the native species. In this regard, the reduced PF4 folding transition is thermodynamically linked with dimer formation which stabilizes tertiary structure. Monomer-dimer association equilibria for reduced PF4 essentially follow the same pH and salt titration trends as reported previously for native PF4 dimers [Mayo, K. H., & Chen, M. J. (1989) Biochemistry 28, 9469-9478], indicating that that dimer interface is generally conserved in the absence of disulfide constraints. Reduced PF4 tetramers are not apparent under any conditions investigated, suggesting that disulfides are necessary for efficient antiparallel beta-sheet alignment between dimer pairs.

Pupil diameter and the principal ray

Placement of the surgical zone is critical in refractive procedures that alter a portion of the corneal curve. An improperly centered optical zone may produce glare, decrease best corrected visual acuity, and decrease contrast sensitivity. For proper placement, the new surface should be centered around the line of sight, which is the principal ray from the object of regard that passes through the image of the patient's pupil as projected on the cornea. This point is not necessarily at the geometric center of the cornea and is found by locating the center of the pupil while the patient is maintaining fixation coaxially with the surgeon. However, the pupil does not dilate concentrically and its geometric center moves as the pupil diameter changes. We have found a shift up to 0.7 mm in the geometric center of the pupil as it dilates. Therefore, centration of an ablated or a radial keratotomy zone is most efficiently done when the diameter of the modified corneal optical zone is centered around the line of sight and is superimposed upon the entrance pupil. This will minimize extension of the edge of the large pupil beyond the ablated zone and reduce unwanted secondary optical effects from degrading vision.

Retroperitoneoscopy: foreign body retrieval

Retroperitoneoscopy is a rarely indicated procedure for the urological surgeon. However, it can be a useful means to approach some types of ureteral pathology and foreign bodies. We describe a case in which a severed surgical drain was removed from deep within the retroperitoneum by using a percutaneous retroperitoneal approach.

Platelet factor 4 efficiently reverses heparin anticoagulation in the rat without adverse effects of heparin-protamine complexes

BACKGROUND

It has been observed that the reversal of heparin anticoagulation in humans by protamine sulfate (PS) results in various adverse reactions including leukopenia, thrombocytopenia, activation of complement, increased vascular permeability, systemic hypotension, pulmonary vasoconstriction, and pulmonary edema. The purpose of this study was to compare the efficacy and effects of native platelet factor 4 (PF4) and recombinant platelet factor 4 (rPF4) with those of PS in heparin neutralization in vivo, using a rat model.

METHODS AND RESULTS

Sprague-Dawley rats were anesthetized with sodium pentobarbital, and the right femoral vein and carotid artery were cannulated. For determination of activated partial thromboplastin time, platelet count, white blood cell count, and complement titer, arterial blood samples were taken before and immediately after heparin (10 units/100 g) infusion and at several time points after the infusion of the neutralizing agent (PS, 0.1 mg/100 g; PF4, 0.5 mg/100 g). In separate groups of animals, mean arterial blood pressure was monitored throughout identical protocols and the lungs were prepared for histological examination. The anticoagulant activity of heparin was effectively reversed by all of the neutralizing agents (PS, PF4, and rPF4). Platelet count (48% of initial), white blood cell count (52% of initial), complement titer (60% of initial), and mean arterial pressure (20% decrease) decreased significantly in heparinized animals receiving PS but not in those receiving PF4 or rPF4. Lung interstitium appeared normal when heparin was followed by PF4; however, interstitial edema and hemorrhage were observed with heparin-PS.

CONCLUSIONS

These results suggest that PF4 efficiently reverses heparin anticoagulation in the rat without the adverse effects of heparin-protamine complexes. Therefore, rPF4 may be an appropriate substitute for PS in patients undergoing cardiovascular surgery and other procedures that require heparin anticoagulation.

Effect of temporary occlusion of hypogastric arteries on blood loss during radical retropubic prostatectomy

We report on a prospective, partially randomized study of 130 patients, examining the effect of temporary occlusion of the hypogastric arteries on intraoperative blood loss, perioperative blood replacement and change in preoperative to postoperative hematocrit. We observed no significant difference in any of these parameters when comparing patients who did and did not undergo intraoperative occlusion of the hypogastric arteries. These findings suggest that temporary occlusion of the hypogastric arteries during radical prostatectomy does not have a major effect on the blood loss associated with this operation. Extensive collateral circulation to the prostate and a substantial venous component of blood loss may explain these findings. Banking of 3 units of autologous blood preoperatively would have decreased the need for homologous transfusions in the majority of patients.

Expression and purification of active recombinant platelet factor 4 from a cleavable fusion protein

A synthetic gene for human platelet factor 4 (hPF4) has been expressed at high levels as a fusion protein in Escherichia coli. The hPF4 sequence has been cleaved from the fusion protein by cyanogen bromide treatment and purified by column chromatography. Like hPF4, our recombinant hPF4 (rhPF4) is tetrameric under physiological conditions, binds heparin, and inhibits angiogenesis. Extensive purification to remove trace amounts of uncleaved fusion protein completely from the desired product rhPF4 was difficult. We have exploited recombinant DNA technology by modifying the fusion moiety to accomplish separation. This type of modification, which did not affect expression level, could be applied to other recombinant fusion proteins.

Long-term followup of patients treated with 1 or 2, 6-week courses of intravesical bacillus Calmette-Guerin: analysis of possible predictors of response free of tumor

We report our long-term experience with 104 patients treated for recurrent superficial bladder tumors followed for a mean of 48 +/- 2 months (range 6 to 83 months). Patients received 6 weekly intravesical bacillus Calmette-Guerin instillations, and were followed for response with urinary cytology, cystoscopy and bladder biopsy. Patients were considered treatment failures if either urinary cytology or biopsy results were positive for tumor. Of 69 patients who failed the initial treatment course 60 were given an additional 6-week course of therapy. A 6-week course of bacillus Calmette-Guerin was successful in 19 of 55 patients (35%) treated for prophylaxis, 10 of 32 (31%) treated for carcinoma in situ and 6 of 17 (35%) treated for residual tumor. The response rate for the total patient population treated with 1, 6-week course was 34% (35 of 104). Another 6-week course was successful in 32 of 60 patients (53%). The over-all response rate free of tumor for patients treated with either 6 or 12 weeks of therapy was 64%. The mean interval free of tumor was 48 months. We evaluated tumor type, stage and grade in conjunction with muscle invasion to assess potential indicators of response to a second course of bacillus Calmette-Guerin. Of 13 patients with carcinoma in situ and 45 with papillary disease 5 (38%) and 26 (58%), respectively, responded to a second course of bacillus Calmette-Guerin (not significantly different). In contrast, 5 of 8 carcinoma in situ failures (63%) had muscle invasive disease, compared to only 3 of 19 papillary nonresponders (16%) (p less than 0.02). These results suggest that intravesical bacillus Calmette-Guerin for the treatment of superficial bladder tumors is an effective long-term therapy. One 6-week course may be ineffective for some patients and another 6-week course provides long-term survival free of tumor for many course 1 failures. Patients who present with carcinoma in situ after a single 6-week course of intravesical bacillus Calmette-Guerin have a significantly higher risk for muscle invasive disease than those with recurrent papillary tumors.

Transplantation: the role of immunohematologic services

The role of the immunohematologic services in transplantation is described. Provision of blood products for transplantation is necessary for prevention of alloimmunization or graft rejection, graft versus host disease secondary to transfusion, and transfusion-transmissible diseases in an immunosuppressed patient while avoiding unnecessary donor exposure. Requirements differ with different types of transplants. The transfusion service needs to provide products according to the specific needs of the transplant recipient and establish protocols for each different transplantation program.

Changes in gene expression during nitrogen starvation in Anabaena variabilis ATCC 29413

When the filamentous, nitrogen-fixing cyanobacterium Anabaena variabilis ATCC 29413 was subjected to nitrogen starvation under aerobic conditions, a complex series of events was initiated which resulted in heterocyst formation and derepression of the ability to fix dinitrogen. Using DNA-RNA hybridization techniques, we monitored the expression of several genes during nitrogen starvation and correlated changes in the mRNA levels with changes in enzyme activity, protein levels, and morphology. Nitrogenase mRNA was first observed after about 8.5 h of nitrogen starvation, as was nitrogenase activity. Late proheterocysts were present at that time. The level of nitrogenase mRNA increased for 5 to 6 h and then leveled off. Phycocyanin and allophycocyanin mRNA levels decreased rapidly within 1 h of nitrogen starvation; the levels increased later, as nitrogen starvation was alleviated, first by protein breakdown and then by nitrogen fixation. The average half-life of A. variabilis mRNA was determined by pulse-labeling techniques to be 16 to 18 min. Hybridization analysis showed that cpc and apc mRNAs also had half-lives of 16 to 18 min; the half-lives were not significantly different under nitrogen starvation conditions. Our results support the idea that the changes induced by nitrogen starvation are primarily the result of transcriptional regulation.

Cyanide-induced parkinsonism: clinical, MRI, and 6-fluorodopa PET studies

A 46-year-old man ingested 1,500 mg of potassium cyanide in a suicide attempt. He survived, but later developed a severe parkinsonian syndrome. MRI revealed multiple areas of low-signal intensity in the globus pallidus and posterior putamen. A 6-fluorodopa PET study revealed bilateral decreased uptake in the basal ganglia. This evidence of functional impairment of dopaminergic nigrostriatal neurons is related either to direct toxicity of cyanide or to the effects of cerebral hypoxia secondary to cyanide intoxication.

In-vivo secondary structure analysis of the small nuclear RNA U1 using psoralen cross-linking

Intramolecular base-pairing interactions have been probed in the small nuclear RNA U1 in vivo. HeLa cells were treated with the psoralen derivative aminomethyltrioxsalen, and cross-linking was carried out by irradiating the intact cells with light of 365 nm wavelength. Cross-linking resulted in a discrete shift in electrophoretic mobility of approximately 65 to 70% of the U1. This intramolecularly cross-linked U1 RNA, termed XU1, was purified and shown to co-migrate with uncross-linked U1 upon photo-reversal of psoralen cross-links with light of 254 nm wavelength. XU1 was also generated by the in-vitro cross-linking of deproteinized U1, suggesting that the secondary structure of U1 RNA in solution is similar to that of U1 ribonucleoprotein in the cell. A sequencing analysis was developed, based on partial enzymatic and alkaline cleavage of psoralen-treated RNA, to identify the position of psoralen cross-links and to distinguish between psoralen monoadducts and diadducts (cross-links). Sequencing of 3' and 5' end-labeled XU1 provided direct evidence for the presence of a unique intramolecular cross-link in XU1, located on uridine 116 (U116). This result is consistent with several secondary-structure models for U1 in which U116 is located in a base-paired stem. The proximity of uridine 96 (U96) to U116 on the opposite side of the base-paired stem suggested that U116 was cross-linked to U96. An additional U1 species having an electrophoretic mobility between those of U1 and XU1 was also generated by psoralen treatment. Analysis of this U1 species, termed U1M, revealed a psoralen monoadduct on U96. Further longwave (365 nm) irradiation of purified U1M resulted in its conversion to XU1 by completion of the U96-U116 cross-link. This suggested that cross-linking at the U96-U116 site occurred as a two-step process in which the psoralen first reacted with U96 and then with U116. Sequencing analysis also identified a psoralen monoadduct on uridine 45 (U45) of XU1. Efficient psoralen-adduct formation, which resulted in cross-linking at the U96-U116 site and monoaddition on U45, suggests that these regions are relatively accessible in the native U1 small nuclear ribonucleoprotein particle in vivo.

Stepwise shortening of muscle fibre segments

Shortening dynamics were measured in single fibres of frog skeletal muscle using a system that could track the spacing between hairs mounted on the fibre surface. Segment length changes were predominantly stepwise. The objective of the study was to identify potential artifacts and check their relevance. Several possible causes of artifactual steps were evaluated quantitatively and ruled out. In addition, the surface marker method and an independent length-detection method based on light diffraction were used simultaneously. The concurrence of results confirmed that it is highly unlikely that stepwise shortening could arise out of instrument artifact. Possible mechanisms underlying the phenomenon are considered.

Purification and characterization of the gene 1.2 protein of bacteriophage T7

Gene 1.2 of bacteriophage T7, located near the primary origin of DNA replication at position 15.37 on the T7 chromosome, encodes a 10,059-dalton protein that is essential for growth on Escherichia coli optA1 strains (Saito, H., and Richardson, C. C. (1981) J. Virol. 37, 343-351). In the absence of the T7 1.2 and E. coli optA gene products, the degradation of E. coli DNA proceeds normally, and T7 DNA synthesis is initiated at the primary origin. However, T7 DNA synthesis ceases prematurely and the newly synthesized DNA is degraded; no viable phage particles are released. The gene 1.2 protein has been purified to apparent homogeneity from cells in which the cloned 1.2 gene is overexpressed. Purification of the [35S] methionine-labeled protein was followed by monitoring the radioactivity of the protein and by gel electrophoresis. The purified protein has been identified as the product of gene 1.2 on the basis of molecular weight and partial amino acid sequence. We have found that extracts of E. coli optA1 cells infected with T7 gene 1.2 mutants are defective in packaging exogenous T7 DNA when such extracts are prepared late in infection. Purified gene 1.2 protein restores packaging activity to these defective extracts, thus providing a biological assay for gene 1.2 protein. No specific enzymatic activity has been found associated with the purified gene 1.2 protein.

Gene 1.2 protein of bacteriophage T7. Effect on deoxyribonucleotide pools

The gene 1.2 protein of bacteriophage T7, a protein required for phage T7 growth on Escherichia coli optA1 strains, has been purified to apparent homogeneity and shown to restore DNA packaging activity of extracts prepared from E. coli optA1 cells infected with T7 gene 1.2 mutants (Myers, J. A., Beauchamp, B. B., White, J. H., and Richardson, C. C. (1987) J. Biol. Chem. 262, 5280-5287). After infection of E. coli optA1 by T7 gene 1.2 mutant phage, under conditions where phage DNA synthesis is blocked, the intracellular pools of dATP, dTTP, and dCTP increase 10-40-fold, similar to the increase observed in an infection with wild-type T7. However, the pool of dGTP remains unchanged in the mutant-infected cells as opposed to a 200-fold increase in the wild-type phage-infected cells. Uninfected E. coli optA+ strains contain severalfold higher levels of dGTP compared to E. coli optA1 cells. In agreement with this observation, dGTP can fully substitute for purified gene 1.2 protein in restoring DNA packaging activity to extracts prepared from E. coli optA1 cells infected with T7 gene 1.2 mutants. dGMP or polymers containing deoxyguanosine can also restore packaging activity while dGDP is considerably less effective. dATP, dTTP, dCTP, and ribonucleotides have no significant effect. The addition of dGTP or dGMP to packaging extracts restores DNA synthesis. Gene 1.2 protein elevates the level of dGTP in these packaging extracts and restores DNA synthesis, thus suggesting that depletion of a guanine deoxynucleotide pool in E. coli optA1 cells infected with T7 gene 1.2 mutants may account for the observed defects.

The influence of diazepam on the serum protein binding of bupivacaine at normal and acidic pH

Since both bupivacaine and diazepam are highly protein bound, it is possible that a drug displacement interaction could occur, resulting in an increase in free bupivacaine concentration that could exacerbate systemic toxicity. This study was undertaken to characterize the serum binding of diazepam and to evaluate any drug displacement interaction between diazepam and bupivacaine. Human serum obtained from venous blood of normal male and female volunteers was used for measurements of protein binding using an Amicon Micropartition System. Bupivacaine protein binding in the presence of 0, 0.5 and 1.5 microgram/ml diazepam was best described by the model for two classes of binding sites. Neither concentration of diazepam significantly altered the capacity or affinity for either class of bupivacaine binding sites when compared to control. Free concentrations of bupivacaine were statistically identical in the presence of both diazepam concentrations. The complete diazepam binding profile in both serum and isolated human serum albumin was best described by a model describing two classes of binding sites. The effect of an acidic pH on bupivacaine was also independent of diazepam concentration. Diazepam protein binding was not affected by a reduction in pH from 7.4 to 7.0. The data reported here suggest no binding displacement interaction exists between bupivacaine and concomitantly administered diazepam. Thus, administration of diazepam during a toxic reaction associated with bupivacaine should not alter free bupivacaine concentration.

Continuous perineural infusions of bupivacaine for prolonged analgesia--a rapid two-point method for estimating individual pharmacokinetic parameters

Results of previous studies have shown a 5-10 fold range in the clearance total and half-life of bupivacaine. Since bupivacaine has a narrow therapeutic range and highly variable pharmacokinetic parameters, rapid estimation of the parameters allows early dosage regimen adjustments, and hence, better pain management. The pharmacokinetic parameters in 17 patients were estimated based on two samples drawn within 18 h after initiation of therapy. Based on the estimated parameters, a later sample's concentration was predicted. Results of this study confirm the previously reported large variation in pharmacokinetic parameters. An excellent agreement between actual and predicted concentration was found. The use of this method allows early readjustment in the dosage regimen, resulting in effective pain management without compromising patient safety.

The clinical relevance of the drug displacement interaction between meperidine and bupivacaine

The effect of meperidine at two clinically relevant concentrations (0.4 and 0.8 microgram/ml) on the serum protein binding of bupivacaine was studied. The serum protein binding profile for meperidine was characterized over a wide concentration range (0.5-100 micrograms/ml). All bupivacaine binding experiments were characterized by a two classes of binding sites model. Bupivacaine binding was independent of added meperidine. Meperidine binding was characterized by a one class of binding sites model and the unbound meperidine concentration was relatively constant over the entire range studied. The capacity and affinity of the meperidine binding site are suggestive of binding primarily to albumin. At clinically encountered meperidine concentrations, no increased toxicity due to an increase in unbound bupivacaine would be expected.

Influence of cimetidine on bupivacaine disposition in rat and monkey

Recent reports have appeared describing a cimetidine-induced alteration in either the input or disposition function for many drugs. The total clearance component of the disposition function is the primary perturbation. In the present investigation, the influence of cimetidine on bupivacaine disposition was studied, using in vitro and in vivo models. Since the extraction ratio for bupivacaine is low, total clearance follows the capacity-limited theory. Hence, the influence of cimetidine on the intrinsic clearance of bupivacaine was assessed using microsome and hepatocyte models. Results for both systems are in excellent agreement and indicate a noncompetitive inhibition. Additionally, the influence of cimetidine on the protein-binding profile of bupivacaine was determined. In the presence of cimetidine, the these findings was assessed in vivo in rhesus monkeys. co-administration of cimetidine resulted in an increase in the volume of distribution at steady state and no change in the total clearance of bupivacaine.

The influence of lactic acid on the serum protein binding of bupivacaine: species differences

Various animal models have been used for studies of bupivacaine cardiovascular toxicity. These studies are difficult to relate to the clinical situation, since the disposition of bupivacaine in the various species is unknown. The serum protein binding of bupivacaine, therefore, was determined in human, sheep, monkey, dog, and rat at physiologic pH using ultrafiltration. Since a mixed acidosis results during a systemic toxicity reaction to bupivacaine, the influences of an acidic pH, resulting from the addition of lactic acid, also was examined. All sera exhibited two classes of binding sites, a high-affinity, low-capacity class (class 1) and a low-affinity, high-capacity class (class 2). When compared to human serum at physiologic pH, a significantly higher (P less than 0.05) affinity constant for the class 1 sites was observed for all species studied, with the exception of the rat. All species studied exhibited a significantly lower (P less than 0.05) capacity for the class 1 sites. The binding parameters of the class 2 sites displayed no significant difference. An acid pH resulted in a decrease in bupivacaine protein binding over the entire concentration range studied for all species, with the exception of the monkey. Monkey serum exhibited no change in bupivacaine binding with a decrease in pH. Since protein binding explains only a portion of the total disposition of bupivacaine, further delineation of each animal model under both acidotic and physiologic conditions needs to be accomplished before the animal studies currently under investigation can be extrapolated to the clinical situation.

Bupivacaine protein binding in the term parturient: effects of lactic acidosis

The effects of lactic acidosis on bupivacaine serum protein binding was studied in a group of term parturients and a group of nonpregnant female control subjects. Groups were matched in age and health. Distribution characteristics of bupivacaine in pregnancy were determined. Bupivacaine protein binding was best characterized by the model for two classes of binding sites in all studies. The parturients exhibited a lower capacity for the high-affinity, low-capacity (alpha 1-acid glycoprotein) site and higher affinity for the low-affinity, high-capacity (albumin) site. Lactic acidosis decreased the affinity constant for the high-affinity, low-capacity site in the control group but did not change binding characteristics in the parturients. Free concentration of bupivacaine (Cu) was elevated at low total bupivacaine concentrations (Ct) (less than 10 micrograms/ml). No differences in Cu were detected at concentrations in the cardiotoxic range (greater than 20 micrograms/ml). The Cu values predicted by the estimated binding parameters from in vitro experiments were compared with actual Cu measured in nine parturients at delivery; they correlated significantly (r = 0.94). Distribution changes for bupivacaine in the parturients were consistent with known physiologic changes in body composition associated with pregnancy. Alterations that occur in serum protein binding during pregnancy should not result in increased risk of central nervous system or cardiovascular system toxicity since these alterations do not increase free tissue concentration.

Generalized seizures and cocaine abuse

Cocaine is a commonly abused drug. We report three patients who had generalized seizures immediately following intravenous injection of cocaine. Previous experimental and clinical literature have documented a relationship between cocaine and convulsions. The rising incidence of cocaine use may be associated with a rising incidence of cocaine-associated seizures.