[Visual field progression in glaucoma: cluster analysis]

BACKGROUND

Visual field progression analysis is one of the key points in glaucoma monitoring, but distinction between true progression and random fluctuation is sometimes difficult. There are several different algorithms but no real consensus for detecting visual field progression. The trend analysis of global indices (MD, sLV) may miss localized deficits or be affected by media opacities. Conversely, point-by-point analysis makes progression difficult to differentiate from physiological variability, particularly when the sensitivity of a point is already low. The goal of our study was to analyse visual field progression with the EyeSuite™ Octopus Perimetry Clusters algorithm in patients with no significant changes in global indices or worsening of the analysis of pointwise linear regression.

PATIENT AND METHOD

We analyzed the visual fields of 162 eyes (100 patients - 58 women, 42 men, average age 66.8 ± 10.91) with ocular hypertension or glaucoma. For inclusion, at least six reliable visual fields per eye were required, and the trend analysis (EyeSuite™ Perimetry) of visual field global indices (MD and SLV), could show no significant progression. The analysis of changes in cluster mode was then performed. In a second step, eyes with statistically significant worsening of at least one of their clusters were analyzed point-by-point with the Octopus Field Analysis (OFA).

RESULTS

Fifty four eyes (33.33%) had a significant worsening in some clusters, while their global indices remained stable over time. In this group of patients, more advanced glaucoma was present than in stable group (MD 6.41 dB vs. 2.87); 64.82% (35/54) of those eyes in which the clusters progressed, however, had no statistically significant change in the trend analysis by pointwise linear regression.

CONCLUSION

Most software algorithms for analyzing visual field progression are essentially trend analyses of global indices, or point-by-point linear regression. This study shows the potential role of analysis by clusters trend. However, for best results, it is preferable to compare the analyses of several tests in combination with morphologic exam.

Assessing the impact of source-zone remediation efforts at the contaminant-plume scale through analysis of contaminant mass discharge

The long-term impact of source-zone remediation efforts was assessed for a large site contaminated by trichloroethene. The impact of the remediation efforts (soil vapor extraction and in-situ chemical oxidation) was assessed through analysis of plume-scale contaminant mass discharge, which was measured using a high-resolution data set obtained from 23 years of operation of a large pump-and-treat system. The initial contaminant mass discharge peaked at approximately 7kg/d, and then declined to approximately 2kg/d. This latter value was sustained for several years prior to the initiation of source-zone remediation efforts. The contaminant mass discharge in 2010, measured several years after completion of the two source-zone remediation actions, was approximately 0.2kg/d, which is ten times lower than the value prior to source-zone remediation. The time-continuous contaminant mass discharge data can be used to evaluate the impact of the source-zone remediation efforts on reducing the time required to operate the pump-and-treat system, and to estimate the cost savings associated with the decreased operational period. While significant reductions have been achieved, it is evident that the remediation efforts have not completely eliminated contaminant mass discharge and associated risk. Remaining contaminant mass contributing to the current mass discharge is hypothesized to comprise poorly accessible mass in the source zones, as well as aqueous (and sorbed) mass present in the extensive lower-permeability units located within and adjacent to the contaminant plume. The fate of these sources is an issue of critical import to the remediation of chlorinated-solvent contaminated sites, and development of methods to address these sources will be required to achieve successful long-term management of such sites and to ultimately transition them to closure.

Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions

Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International Space Station (ISS). Tests included single or combined simulated space and Martian conditions. Responses were analysed both by cultural and microscopic methods. Thereby, colony formation capacities were measured and the cellular viability was assessed using live/dead dyes FUN 1 and SYTOX Green. The results clearly suggest a general good resistance of all the samples investigated. C. minteri CCFEE 5187, C. antarcticus CCFEE 515 and colonized rocks were selected as suitable candidates to withstand space flight and long-term permanence in space on the ISS in the framework of the LIchens and Fungi Experiments (LIFE programme, European Space Agency).

Impact of in situ chemical oxidation on contaminant mass discharge: linking source-zone and plume-scale characterizations of remediation performance

A large-scale permanganate-based in situ chemical oxidation (ISCO) effort has been conducted over the past ten years at a federal Superfund site in Tucson, AZ, for which trichloroethene (TCE) is the primary contaminant of concern. Remediation performance was assessed by examining the impact of treatment on contaminant mass discharge, an approach that has been used for only a very few prior ISCO projects. Contaminant mass discharge tests were conducted before and after permanganate injection to measure the impact at the source-zone scale. The results indicate that ISCO caused a significant reduction in mass discharge (approximately 75%). The standard approach of characterizing discharge at the source-zone scale was supplemented with additional characterization at the plume scale, which was evaluated by examining the change in contaminant mass discharge associated with the pump-and-treat system. The integrated contaminant mass discharge decreased by approximately 70%, consistent with the source-zone-scale measurements. The integrated mass discharge rebounded from 0.1 to 0.2 kg/d within one year after cessation of permanganate injections, after which it has been stable for several years. Collection of the integrated contaminant mass discharge data throughout the ISCO treatment period provided a high-resolution, real-time analysis of the site-wide impact of ISCO, thereby linking source-zone remediation to impacts on overall risk. The results indicate that ISCO was successful in reducing contaminant mass discharge at this site, which comprises a highly heterogeneous subsurface environment. Analysis of TCE sediment concentration data for core material collected before and after ISCO supports the hypothesis that the remaining mass discharge is associated in part with poorly accessible contaminant mass residing within lower-permeability zones.

Pharmacological treatment of traumatic brain injury: a review of agents in development

Successful treatment strategies for patients with traumatic brain injury (TBI) remain elusive despite standardised clinical treatment guidelines, improved understanding of mechanisms of cellular response to trauma, and a decade of clinical trials aimed at identifying therapeutic agents targeted at mediators of secondary injury. The information explosion relative to mechanisms of secondary injury has identified several potential targets for intervention. Depending on the type of injury to the brain and the intensity and the success of resuscitation, necrosis, apoptosis, inflammatory and excitotoxic cellular damage can be seen. These same processes may continue postinjury, depending on the adequacy of clinical care. Each of these mechanisms of cellular damage can initiate a cascade of events mediated by endogenous signals that lead to secondary neurological injury. Several factors contributed to the failure of earlier clinical trials. Now that these have been recognised, a positive impact on future drug development in TBI has been realised. Both the US and Europe have organised brain injury consortiums where experts in the treatment of TBI provide insight into study design, implementation, conduct and oversight in conjunction with the pharmaceutical industry. Consequently, future clinical trials of new investigational treatments have greater potential for identifying therapies of merit in specific populations of patients with TBI. Pharmacological strategies under investigation are targeting sites involved in the secondary cascade that contribute to overall poor outcome following the primary injury. These treatments include ion channel antagonists including calcium channel antagonists, growth factors, antioxidants, stem cells, apoptosis inhibitors, and inhibitors of other signal modulators. In conclusion, the complexity of TBI pathology and the mechanisms contributing to secondary injury present unique therapeutic challenges. Appropriate research targets for intervention continue to be investigated, however, the likelihood of improving outcomes with a single approach is extremely small. There is a need for collaborative efforts to investigate the optimal time for drug administration and the logical sequence or combination of treatments that will ultimately lead to improved neurological outcomes in this population.

Postpyloric enteral feeding costs for patients with severe head injury: blind placement, endoscopy, and PEG/J versus TPN

This study describes the advantages and disadvantages of several forms of enteral nutrition for patients with severe head injury (Glasgow Coma Scale Score [GCS], <12). Included in the study are nasoenteric nutrition delivery using blind, endoscopic, percutaneous endoscopic gastrostomy (PEG) and PEG with jejeunostomy (PEG/J), and open jejeunostomy tube placement methods. These methods are compared with parenteral delivery of nutrition. The study constituted a retrospective analysis of the success rate of early enteral feedings by blind, endoscopic PEG and PEG/J and by open jejeunostomy placement of small-bowel feeding tubes for 57 patients with severe head injury. The delivery cost of enteral nutrition per intensive care unit day was compared to the delivery cost of parenteral nutrition per intensive care unit day in the same group of patients. Fifty-three percent of patients were adequately maintained nutritionally with nasoenteric delivery alone and did not require parenteral feeding. The average number of days for initiation of either enteral or parenteral feedings was 1.8 +/- 0.2 days from injury [standard error of mean (SEM); range, 0-10 days]. An average of 3.3 days (range, 0-23 days) was required for feeding tube placement in all patients. For 70% of patients, tube placement was completed within 48 h after injury. Full-strength, full-rate enteral feedings were achieved by a mean of 4.9 days after injury. A total of 128 feeding tubes were placed while the patients were in the intensive care unit (ICU; 2.2 +/- 0.2 tubes per patient). Blind placement of feeding tubes into the small bowel was rarely achieved without repositioning. Endoscopic tube placement into the duodenum was achieved in 50% of patients, into the jejunum for 33% of patients, and into the stomach for 18% of patients. While in the intensive care unit, patients received an average of 77 +/- 2% of their measured energy expenditure (range, 57-114%). Eleven percent of patients experienced severe gastrointestinal problems. Other problems were associated with the inability to achieve or maintain access: dislodged tubes (30%), clogged or kinked tubes (21%), and mechanical access problems (7 %). Seventy-one percent of patients in barbiturate coma were able to tolerate early nasoenteric feedings. Aspiration pneumonitis occurred equally among patients fed nasogastrically and those fed nasoenterically. The overall aspiration rate was 14%. The cost of acute enteral feeding was $170 per day and that for parenteral feeding, $308 per day. We conclude that blind transpyloric feeding tube placement is difficult to achieve in patients with severe head injury; endoscopically guided placement is a better option. Endoscopic feeding tube placement most consistently allows for early enteral nutritional support in severe head injured patients. Limitations include the inability to establish and/or maintain enteral access, increased intracranial pressure, unstable cervical spinal injuries, facial fractures, and dedication of the physician to tube placement and monitoring.

Alpha1-acid glycoprotein concentrations and cerebrospinal fluid drug distribution after subarachnoid hemorrhage

STUDY OBJECTIVE

To test the hypothesis that changes in alpha1-acid glycoprotein (AAG) concentration alter central nervous system (CNS) drug distribution after subarachnoid hemorrhage.

DESIGN

Two-phase, prospective study.

SETTING

University-associated medical center.

PATIENTS

Twenty-one patients with subarachnoid hemorrhage.

INTERVENTION

In phase I, serum AAG concentrations of patients with subarachnoid hemorrhage were measured serially and compared with those in 21 controls undergoing elective neurosurgical procedures. In phase II, nimodipine was the pharmacologic probe to determine the relationship between drug distribution into the CNS and changes in AAG concentration.

MEASUREMENTS AND MAIN RESULTS

Serum and cerebrospinal fluid (CSF) samples were collected from patients with subarachnoid hemorrhage treated with nimodipine and used to measure total and unbound drug concentrations. Concentrations of AAG were 39% higher in patients than in controls preoperatively. They decreased significantly by 24 hours after surgery in patients and increased in controls. In both groups the concentrations were higher than reported normal values. During the period of reduced AAG concentration, calculated unbound nimodipine concentrations were 3-fold higher (p<0.05) than at later periods, with a trend toward higher total concentrations. Overall, mean CSF nimodipine concentration was 6.4% of mean serum total concentration. The CSF concentrations decreased as AAG concentrations increased, independent of serum concentrations (r = -0.52, p<0.02).

CONCLUSION

Concentrations of AAG change after subarachnoid hemorrhage and are transiently influenced by surgery. Unbound drug concentration increases when AAG concentrations decrease, whereas CSF concentrations decrease when AAG concentrations increase. These preliminary findings suggest that changes in AAG concentrations can alter unbound serum nimodipine concentrations and may affect CSF drug distribution.

High dose-rate afterloading 192Iridium prostate brachytherapy: feasibility report

BACKGROUND

RESULTS from localized prostate cancer series using seed implants have been most encouraging. However, with current techniques, inadequate dosimetry sometimes occurs. Remote afterloading high dose rate 192Iridium brachytherapy (HDR-Ir192) theoretically remedies some potential inadequacies of seed implantation by performing the dosimetry after the needles are in place. This study was undertaken to determine the feasibility of incorporating multifractionated HDR-Ir192 in the brachytherapy management of prostate carcinoma.

METHODS

From October 1989 to August 1995, 104 patients were treated with a combination of multifractionated HDR-Ir192 and external beam. Patients ranged in age from 48-78 years, with a mean of 68.6 years. By TNM clinical stage, there were 1 T1b, 31 T1c, 28 T2a, 24 T2b, 9 T2c, 8 T3a, and 3 T3c lesions. For the group, the mean initial pretreatment PSA was 12.9 ng/ml (median 8.1), with 90% of the patients having had a pretreatment PSA greater than a normal value of 4.0 ng/ml. Patients with prostate volumes up to 105 cc were implanted. Treatment was initiated with perineal needle placement using ultrasound guidance. A postoperative CT scan was obtained to provide the basis for treatment planning. Four HDR-Ir192 treatments were given over a 40-h period, with a minimal peripheral dose (MPD) ranging from 3.00 to 4.00 Gy per fraction over the course of this study. Two weeks later, external beam radiation was added using 28 fractions of 1.80 Gy daily, to a dose of 50.40 Gy.

RESULTS

Follow-up ranged from 10 to 89 months, with a mean of 46 months and median of 45 months. At various follow-up points, the patient numbers at risk were: 1 year, 101; 3 years, 69; 5 years, 28. The technique proved to be uniformly applicable to a wide range of prostate volumes and was very well tolerated by patients. Nearly all significant late in-field treatment complications were genitourinary in nature. Of the patients, 6.7% developed urethral strictures that were readily manageable. Changes in technique implemented in 1993 appear to have significantly lessened the incidence of this complication. Two patients developed significant uropathy within the first treatment year, but both resolved; 1 of these 2 patients had a prior TURP. Other bladder or rectal complications have been minimal. Using PSA progression as a marker of tumor response, approximately 84% of patients whose initial PSA was less than 20 ng/ml were free of progression at 5 years by actuarial analysis.

CONCLUSIONS

We found the use of transperineal ultrasonography, postimplant CT-based dosimetry, coupled with adjustable dose delivery inherent to remote afterloading technology, to give unparalleled control in performing this complex brachytherapy task. Thus, it may be advantageous in certain clinical situations where the resultant MPD is needed to reliably cover the target volume, such as in patients with carcinomas at base locales, when the possibility of moderate to extensive intraprostatic tumor exists, and in patients with large glands. Early PSA data suggest that it may be effective as a definitive treatment with rates of adverse late tissue effects that are acceptable using current technique and doses described herein. Longer follow-up is needed to ascertain its position among the various treatment regimens for prostate carcinoma.

New and investigational treatment options for ischemic stroke

We conducted a MEDLINE search of new treatment strategies and experimental agents for treating acute ischemic stroke published from 1989-1996. Clinical trials involving thrombolytics, glutamine release inhibition, N-methyl-D-aspartate receptor antagonism, opioid antagonism, calcium channel blockade, free radical scavenging, membrane stabilization, intercellular adhesion molecule-1 antagonism, ganglioside administration, and growth factor administration were included. Basic research articles were selected based on progress of the therapeutic class toward clinical trials. Approval of tissue plasminogen activator indicates progress in new treatments for acute ischemic stroke. Experimental therapies with potential may become available soon. Recognizing signs and symptoms of stroke is crucial to ensure prompt administration of these agents. The time to diagnosis determines the therapeutic approach for acute ischemic stroke.

Intravenous insulin-like growth factor-I (IGF-I) in moderate-to-severe head injury: a Phase II safety and efficacy trial

The purpose of this study was to determine the effect of insulin-like growth factor-I (IGF-I) on the catabolic state and clinical outcome of head-injured patients. Thirty-three patients between the ages of 18 and 59 years with isolated traumatic head injury and Glasgow Coma Scale (GCS) scores of 4 to 10 were randomized to one of two groups. All patients received standard neurosurgical intensive care plus aggressive nutritional support; the patients in the treatment group also received intravenous therapy with continuous IGF-I (0.01 mg/kg/hour). During the 14-day dosing period, the control patients lost weight, whereas treated patients gained weight despite a significantly higher measured energy expenditure and lower caloric intake (p = 0.02). Daily glucose concentrations and nitrogen outputs were greater in control patients (p = 0.03) throughout the study period. During Week 1, only treated patients achieved positive nitrogen balance. Fifteen of 17 treated and 13 of 16 control patients survived the 1st week. No deaths occurred in patients whose serum IGF-I concentrations were higher than 350 ng/ml. Dichotomized Glasgow Outcome Scale scores for patients with baseline GCS scores of 5 to 7 improved from poor to good for eight of 12 treated patients but for only three of 11 control patients (p = 0.06). Eight of 11 treated patients with serum IGF-I concentrations that were at least 350 ng/ml achieved moderate-to-good outcome scores at 6 months, compared to only one of five patients with lower concentrations (p < 0.05). These findings indicate that pharmacological concentrations of IGF-I may improve clinical outcome and nitrogen utilization in patients with moderate-to-severe head injury.

Intravenous insulin-like growth factor-I (IGF-I) in moderate-to-severe head injury: a phase II safety and efficacy trial

The purpose of this study was to determine the effect of insulin-like growth factor-I (IGF-I) on the catabolic state and clinical outcome of head-injured patients. Thirty-three patients between the ages of 18 and 59 years with isolated traumatic head injury and Glasgow Coma Scale (GCS) scores of 4 to 10 were randomized to one of two groups. All patients received standard neurosurgical intensive care plus aggressive nutritional support; the patients in the treatment group also received intravenous therapy with continuous IGF-I (0.01 mg/kg/hour). During the 14-day dosing period, the control patients lost weight, whereas treated patients gained weight despite a significantly higher measured energy expenditure and lower caloric intake (p = 0.02). Daily glucose concentrations and nitrogen outputs were greater in control patients (p = 0.03) throughout the study period. During Week 1, only treated patients achieved positive nitrogen balance. Fifteen of 17 treated and 13 of 16 control patients survived the 1st week. No deaths occurred in patients whose serum IGF-I concentrations were higher than 350 ng/ml. Dichotomized Glasgow Outcome Scale scores for patients with baseline GCS scores of 5 to 7 improved from poor to good for eight of 12 treated patients but for only three of 11 control patients (p = 0.06). Eight of 11 treated patients with serum IGF-I concentrations that were at least 350 ng/ml achieved moderate-to-good outcome scores at 6 months, compared to only one of five patients with lower concentrations (p < 0.05). These findings indicate that pharmacological concentrations of IGF-I may improve clinical outcome and nitrogen utilization in patients with moderate-to-severe head injury.

A step-wise protocol for stress ulcer prophylaxis in the neurosurgical intensive care unit

BACKGROUND

Neurosurgical patients are at risk for stress induced gastric erosion. Clinical criteria for monitoring stress ulcer prophylaxis (SUP) efficacy and predicting clinical bleeding are limited. SUP in the neurosurgical intensive care unit (NSICU) was evaluated utilizing a multidisciplinary quality assurance program with defined criteria for therapy.

METHODS

All patients admitted to the NSICU were managed using this protocol. Therapy was initiated with a single drug (cimetidine 300 mg IV every 6 hours, or continuous infusion up to 2400 mg/day) in 136 evaluable cases. Combination therapy was implemented if continued gastric pH < 4 and guaiac positive aspirates occurred (N = 45).

RESULTS

Significant correlations were observed between low gastric pH values and both GCS < 8 (P < or = 0.01) and length of ventilatory support (P < or = 0.005). Single agent therapy was more effective in patients with GCS > or = 8 (P < or = 0.001). Endoscopy was performed in 25 patients. No patient with GCS < 8 had pathologic lesions. The presence of asymptomatic gastrointestinal lesions was higher in patients requiring longer ventilatory support (P < or = 0.001) and intensive care unit stay (P < or = 0.0001). Patients requiring pentobarbital and vasopressors had statistically higher rates of clinical bleeding (P < 0.05). Patients with GCS < 8 had increased rates of pneumonia (P < or = 0.005) with a higher pneumonia rate when treated with combination therapy (P < or = 0.05). Overall, the incidence of clinical bleeding was 3.7%.

CONCLUSIONS

This protocol was effective for prospective monitoring of SUP efficacy and limited multiple drug therapy to patients at risk for clinical bleeding.

New pharmacologic strategies for acute neuronal injury

The number of new drugs for treating neurotrauma is rapidly expanding. Emerging theories regarding the mechanisms of secondary neuronal injury provide the scientific basis for evaluating these new agents. Some of the most promising mechanisms for intervention are ionotropic channel antagonism, inhibition of lipid peroxidation, and neurotrophic factor augmentation. Many of these new agents are undergoing clinical trials to establish their roles in therapy.

New pharmacologic approaches to acute spinal cord injury

The incidence of spinal cord injury (SCI) in the United States is approximately 10,000 new cases per year. Strategies to prevent injury or salvage a few dermatomal levels may have significant effects on outcome. Several pharmacologic agents have been evaluated for their efficacy in patients with acute SCI. Methylprednisolone, when administered early, was the first drug to show significant improvement in outcome and is a standard of comparison for future agents. Several new drugs show promising results in animal models of SCI, with more extensive human trials currently under way. Results of more well-controlled clinical trials are necessary to determine which agents have significant neurologic benefits.

Management of bacterial urinary tract infections in adults

OBJECTIVE

To provide a comprehensive review of the diagnosis and therapeutic management considerations in patients with urinary tract infections (UTIs).

DATA SOURCES

A MEDLINE search was used to identify pertinent English language literature, including reviews. Infectious disease textbooks were used for background information.

STUDY SELECTION

Clinical trials evaluating drug therapy in a variety of patient populations with UTIs were reviewed.

DATA EXTRACTION

Background information was obtained from comprehensive reviews. Drug dosing strategies and efficacy comparisons were extracted from the investigations in this area.

DATA SYNTHESIS

Information was processed to provide general guidelines and resources for practitioners to use in managing UTIs.

CONCLUSIONS

There are a number of useful antibiotics for the management of UTIs. The distinctions between infection severity and underlying risk factors within a given population influence the appropriateness of drug selection and duration of treatment.

A simplified high-performance liquid chromatographic method for direct determination of warfarin enantiomers and their protein binding in stroke patients

A simplified method for direct determination of warfarin enantiomers by high-pressure liquid chromatography with fluorescence detection has been developed. This method involves solid phase extraction of warfarin in plasma, precolumn derivatization to form diastereoisomeric esters, and post-column reaction to discriminate each enantiomer separately. Ultrafiltration was employed in the separation of unbound warfarin enantiomers. Twelve plasma samples from six stroke patients taking warfarin regularly were analyzed. The average concentration of total warfarin was 0.47 +/- 0.17 mg/L for the S-isomer and 0.69 +/- 0.18 mg/L for the R-isomer. The average protein binding was 99.67 +/- 0.33% for S-warfarin and 99.44 +/- 0.33% for R-warfarin. This methodology provides a quick and reliable technique for determining enantiomeric protein binding of warfarin in clinical settings.

Pentobarbital coma in neurosurgical patients: nutrition considerations

Neurosurgical patients in pentobarbital coma are a complex nutrition support population. Physiologic changes associated with the primary injury to the brain, combined with the pharmacodynamic influences of barbiturate therapy, contribute to the difficulties of initiating aggressive nutrition support. Early nutritional repletion is important to the overall outcome of traumatically injured patients. Consequently, factors that influence nutrition support decisions must be understood to assure appropriate intervention. The metabolic changes associated with traumatic head injury, pentobarbital therapy, and nutrition support strategies are reviewed.

Histamine receptor antagonists and lipid stability in total nutrient admixtures

Drug stability and compatibility studies should be performed for all medications added to total nutrient admixtures (TNAs) before administration to patients. The stability of TNA components will vary depending on product selection and final concentrations. This variability prohibits generalizing published study results generically to TNAs containing untested products or combinations. Histamine receptor antagonists (H2RAs) are commonly administered by continuous infusion via nutrient solutions. When the delivery vehicle is a TNA, comparative stability and compatibility studies performed under similar test conditions are lacking. The stability of marketed parenteral H2RAs and of the investigational H2RA, nizatidine was analyzed in TNA solutions containing either Liposyn II or Intralipid at differing concentrations. All H2RAs remained at more than 90% of initial concentration at 24 hours. After 48 hours, only ranitidine concentrations fell to less than 90% in all study solutions. Each TNA containing an H2RA was within pH stability ranges for lipid products, and no change in particle size was detected during the 48-hour period. This is the first report determining H2RA compatibility and stability in TNA solutions with both 3% and 5% Intralipid and Liposyn II and using similar methodology for all standard H2RA concentrations. Results suggest that these drugs are stable for 24 hours in TNAs containing either lipid product. Beyond this time, administration of ranitidine may be unreliable because of poor stability under the conditions tested.

Vancomycin administration into the cerebrospinal fluid: a review

OBJECTIVE

To discuss administering vancomycin directly into the cerebrospinal fluid (CSF) to treat serious central nervous system (CNS) infections.

DATA SOURCES

References were obtained through an online search of MEDLINE, limited to material published in English. In addition, information was extracted from clinical trials, review articles, abstracts, and textbooks.

STUDY SELECTION

Systematic evaluation of this topic in humans has not been done in a prospective manner. Related research articles describing the pathophysiology of CNS infections, intrathecal drug administration, and case reports of CSF vancomycin administration were reviewed.

DATA EXTRACTION

Case reports regarding CSF vancomycin dosing were evaluated and included: drug dosing, infecting organism, infectious disease state, infectious outcome, CSF dynamics/flow abnormalities, methods of drug administration, drug monitoring, and toxicities.

DATA SYNTHESIS

The results of this review are based on qualitative evaluations of anecdotal case reports and a basic understanding of intrathecal and intraventricular drug dosing principles. CSF administration of vancomycin is an effective means of bypassing the blood-brain barrier to achieve greater drug concentrations within the CSF. Current limitations to the CSF administration of vancomycin include a lack of data describing its safety, efficacy, and pharmacokinetics.

CONCLUSIONS

CNS infections may require the CSF administration of vancomycin for successful eradication. Recommendations for dosing in the literature vary. Because of the potential toxicities associated with elevated CSF concentrations of vancomycin, dosing should be conservative.

Appropriateness of antibiotic selection and use in laminectomy and microdiskectomy

The selection and timing of antibiotic prophylaxis in spinal surgery patients were studied. All laminectomy and microdiskectomy cases in which surgical-wound infection had developed within 60 days of surgery during 1990 at a medical center were retrospectively reviewed because of the high rate of postoperative wound infection for these procedures at the institution. The evaluation covered drug selection, the timing of antibiotic administration relative to the surgical incision, culture and susceptibility test results, and the length of the surgical procedure. Surgical-wound infection was found to have developed in 22 (7%) of the 315 patients who underwent laminectomy or microdiskectomy. There was no apparent difference between the infected group and a matched, uninfected control group in either the antibiotic selected or the number of doses given. On the basis of the organisms isolated from the wounds and susceptibility test results, the selection of cefazolin as the antibiotic was appropriate in 17 of the 22 infected patients. However, compared with the control group, the infected group had a significantly higher percentage of patients in whom antibiotics had been given more than two hours before the time of the surgical incision. The policy on administering prophylactic antibiotics was modified; current guidelines include giving the first dose of cefazolin upon the induction of anesthesia and follow-up administration in three hours if the incision has not been closed by then. The selection of a prophylactic antibiotic for spinal surgery patients was appropriate, but the timing of drug administration was usually not optimal.

Growth factors in nutritional support

Protein catabolism occurs in the severely stressed patient despite adequate protein supplementation. Supplementation of endogenous growth factors is one mechanism being evaluated to promote anabolism and improve nitrogen retention. Recombinant technology has provided a means to reproduce these endogenous growth factors. Both recombinant human growth hormone (rGH) and recombinant human insulin-like growth factor-1 (rhlGf-1) are undergoing clinical trials to establish their roles in nutritional support.

Multidisciplinary drug-use evaluation for stress ulcer prophylaxis

A process for creating a multidisciplinary approach to quality assurance within an intensive-care unit is described. A drug-use evaluation program for stress ulcer prophylaxis in the neurosurgical intensive-care unit (NSICU) was developed by a pharmacist with the cooperation of physicians and nurses at the institution. First, the pharmacist worked with the gastrointestinal medicine division to develop indicators for appropriate prophylaxis and monitoring of stress ulcers in patients admitted to the NSICU. The physicians in the neurosurgical division were then given an opportunity to modify or approve the indicators. Before the indicators went into effect as the standard of care, inservice education was provided and pocket cards outlining the criteria were developed. Data were collected on all patients admitted to the NSICU over one year. The data are being reviewed to determine the clinical efficacy and safety of all regimens used, and this information will be used to revise the criteria and influence subsequent prescribing practices in the unit. The program has led to changes in nursing, medical, and pharmacy practice in the unit. Pharmacists can work with other health-care professionals in developing a program to obtain clinically relevant data for a specific group of patients and thus help to improve patient care.

Stability of nizatidine in total nutrient admixtures

The stability of nizatidine in total nutrient admixtures (TNAs) and the effect of the drug on the stability of lipid emulsions in the TNAs were studied. Duplicate 1476-mL amino acid-dextrose base solutions were prepared; nizatidine 300 mg was added to one. TNAs were prepared by adding to 75-mL samples of the base solutions Intralipid (KabiVitrum) or Liposyn II (Abbott) and sterile water as needed to achieve final lipid concentrations of 3% and 5%. Triplicate 100-mL samples for each lipid product and concentration were prepared; fat-free samples containing nizatidine were also studied. The theoretical final nizatidine concentration was 150 micrograms/mL. Samples were stored at 22 degrees C for 48 hours. Initially and at 12, 24, and 48 hours, the samples were visually inspected, tested for pH and particle-size distribution, and assayed by high-performance liquid chromatography for nizatidine concentration. No color change, precipitation, creaming, or oiling out was noted. For the 12 TNAs containing nizatidine, mean solution pH during the study was 5.88; stability of the lipid products requires pH values greater than or equal to 5.5. Particle-size distribution did not differ appreciably between the nizatidine-containing and drug-free TNAs. Nizatidine concentrations remained greater than 90% of the initial concentration. Nizatidine at a theoretical concentration of 150 micrograms/mL was stable for 48 hours at 22 degrees C in TNA solutions containing 3% and 5% Intralipid or Liposyn II and did not appear to affect lipid emulsion stability.

Intravenous ciprofloxacin versus ceftazidime for treatment of nosocomial pneumonia and urinary tract infection

Intravenous ciprofloxacin and ceftazidime were compared for efficacy in the treatment of nosocomial pneumonia and urinary tract infection (UTI). Patients with nosocomial pneumonia were randomized to receive ciprofloxacin (as the lactate salt) 300 mg i.v. every 12 hours or ceftazidime (with sodium carbonate) 2 g i.v. every eight hours. Patients with UTI were randomized to receive ciprofloxacin 200 mg i.v. every 12 hours or ceftazidime 1 g i.v. every eight hours. Sputum and urine specimens were collected before, during, and after therapy. For patients with pneumonia, the organisms most frequently isolated before treatment began were Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, and Proteus mirabilis. Of the 17 pneumonia patients who completed ciprofloxacin treatment, 15 (88%) had resolution of signs and symptoms or improvement. Of the 15 ceftazidime-treated pneumonia patients, 13 (87%) had resolution or improvement. Staphylococcus aureus, Streptococcus species, Acinetobacter species, and K. pneumoniae infections persisted for the ciprofloxacin treatment failures. Infections by Enterobacter cloacae and Acinetobacter species persisted for the ceftazidime treatment failures. For UTI patients, E. coli was the organism most frequently isolated before treatment. All 14 UTI patients who completed treatment showed resolution or improvement. In the ciprofloxacin group two patients were superinfected by Enterococcus species, and in the ceftazidime group there were two superinfections by Enterococcus species and one by Enterobacter cloacae. Intravenous ciprofloxacin was as effective as ceftazidime in the treatment of nosocomial pneumonia and urinary tract infection. Caution should be exercised when treating serious infections by streptococci or staphylococci.

Estimation of creatinine clearance in patients with Cushing's syndrome

The predictive value of the Cockcroft-Gault equation in patients with Cushing's syndrome was evaluated in 23 patients. Patients were subdivided based on total body weight into two groups, obese and nonobese. Estimated creatinine clearance (EClcr) values were obtained by the Cockcroft-Gault method using ideal body weight (IBW) and total body weight (TBW). These values were then compared with a 24-hour measured creatinine clearance (MClcr). EClcr values based on TBW consistently overestimated measured values in all patients (p less than 0.05). In obese patients with Cushing's syndrome IBW predictions were not statistically different. However, linear regression analysis revealed a poor correlation (r = 0.32). Daily creatinine production rates (Ucr) were calculated and contrasted with an appropriate historical control for obese and nonobese subjects. Nonobese patients revealed a marked reduction in total Ucr compared with normal-weight controls (p less than 0.05). Obese patients also showed a reduction in Ucr when compared with a normal obese control population (p less than 0.05). Difficulty in predicting creatinine clearance in patients with Cushing's syndrome appears to be related to alterations in Ucr. These data suggest that the pathophysiologic changes that accompany Cushing's syndrome are sufficient to alter Ucr and may limit the usefulness of existing methods to predict creatinine clearance and renal function in these patients.

The hormonal control of protein N-glycosylation in the developing rabbit mammary gland and its effect upon transferrin synthesis and secretion

Pregnant rabbit mammary gland explants cultured with insulin, prolactin and cortisol, synthesise and secrete transferrin radiolabelled with [3H]leucine or [3H]mannose. Omission of prolactin from the culture medium inhibited the incorporation of [3H]leucine into casein but not transferrin. Total transferrin secreted under these conditions was approx. 75% of the control (+prolactin) value measured by rocket immunoelectrophoresis. Little incorporation of [3H]mannose into transferrin was seen in the absence of prolactin suggesting a lack of glycosylation of the protein. Dual label experiments with [3H]mannose and [14C]leucine confirmed this. The decreased incorporation of [3H]mannose into dolichol linked intermediates suggests a general effect on protein N-glycosylation in the absence of prolactin. Thus, while the synthesis of the polypeptide backbone of transferrin does not require prolactin its glycosylation does.

A mevalonate requirement for maintenance of fatty acid and protein synthesis during hormonally stimulated development of mammary gland in vitro

The effect of compactin on hormonally induced lipogenesis and protein synthesis was studied in vitro in explants of mammary gland from mid-pregnant rabbits. Compactin blocks mevalonate synthesis by the specific inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase, and in this system, culture with 10 microM compactin for 24, 48, and 72 h inhibited incorporation of [1-14C]acetate (but not [2-14C]mevalonate) into sterol by 98, 95, and 86%, respectively. Removal of compactin prior to assay rapidly reversed this effect and was associated with increased tissue 3-hydroxy-3-methylglutaryl-CoA reductase activity. Fatty acid synthesis (measured by incorporation of [1-14C]acetate or [4,5-3H]leucine) and protein synthesis (measured by incorporation of [4,5-3H]leucine) were both inhibited by around 50% after culture with compactin. This inhibition was not rapidly reversed by removal of compactin prior to assay, but it was prevented by inclusion of 1 mM mevalonolactone in the culture medium. After removal of compactin and continued culture in its absence for 24 h with hormones, the normal tissue capacity for fatty acid and protein synthesis was restored, indicating no permanent cell damage. The results suggest a specific requirement for mevalonate (or derived products) for the hormonal maintenance of the increased fatty acid and protein synthesis characteristic of the development of the mammary gland.

The control of sterol synthesis during development of rabbit mammary gland

A 9-fold increase in the rate of conversion of [14C]-acetate to nonsaponifiable lipids was seen on culturing explants of pregnant rabbit mammary gland in the presence of insulin, prolactin, and cortisol. Stimulation of [3H]mevalonate into nonsaponifiable lipid was 3-fold under the same conditions. With both substrates activities were maximal after 24 h in culture. Incorporation of acetate into saponifiable lipid was stimulated 20-fold after 24 h and almost 50-fold after 48 h in the presence of hormones. Radioactivity from [3H]mevalonate was incorporated into saponifiable lipid after 48 h in culture with hormones suggesting an active trans-methyl-glutaconyl shunt at this time. Changes in the rate of acetate conversion to nonsaponifiable lipid correlated well with the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) in the glands of mid-pregnant and mid-lactating rabbits. Enzyme activity rose from 3.3 pmol/min/mg of 100,000 X g pellet protein in the mid-pregnant gland to an apparent value of 15.6 pmol/min/mg of 100,000 X g pellet protein in the lactating gland. When corrected for the very high content of milk protein in this 100,000 X g pellet, the HMG-CoA reductase activity was 36-fold greater in lactating compared to pregnant mammary gland. Hepatic reductase in both pregnant and lactating animals was approximately 25 pmol/min/mg of microsomal protein. This increase in capacity for sterol synthesis in mammary gland during the transition from pregnancy to lactation suggests that this tissue could synthesize a major proportion of milk sterol.

Elevation of serum high density lipoprotein cholesterol by rowachol, a proprietary mixture of six pure monoterpenes

Rowachol, a proprietary choleretic containing 6 pure monoterpenes markedly elevates serum HDL cholesterol (SHDL-C) concentrations in man. The concentration of SHDL-C showed a progressive increase in 16 patients treated with 6-9 capsules of Rowachol daily for periods of 2-28 weeks. There was no accompanying significant change in the concentrations of serum total cholesterol or triglyceride. In view of the significant inverse relationship between SHDL-C concentration and the risk of developing ischaemic heart disease, it is suggested that Rowachol and possibly other terpenes merit further investigation as possible therapeutic agents in the prevention and treatment of atheroma.