Quantitative analysis of the developing rat kidney: absolute and relative volumes and growth curves

The development of the permanent kidney, or metanephros, is a complex process. In the present study, stereological methods were used at the light microscopic level to estimate the absolute volumes and volume densities of seven compartments in the developing rat metanephros, from embryonic day 14 (E14) to E21. Metanephroi from time-mated Sprague-Dawley rats were embedded whole in glycolmethacrylate, exhaustively sectioned at 2 microm and stained with PAS. The left metanephros from three embryos from each of three mothers were analysed at each of the ages (a total of 72 metanephroi). Relative volumes were multiplied by total metanephric volume to obtain absolute volumes. Total metanephric volume increased approximately 300-fold during the 7-day period studied. At E14, 92% of the metanephros was composed of undifferentiated mesenchyme, whilst the ureteric epithelium made up approximately 5% of the volume. By E21 the undifferentiated mesenchyme comprised 47% of the kidney, while the ureteric epithelium comprised 9% and the various components of developing nephrons (epithelial vesicles, comma-shaped bodies, S-shaped bodies, glomeruli, tubules) comprised 43%. Equations with prediction intervals describing the growth of the whole kidney as well as the absolute and relative growth of the seven kidney compartments were generated. These data provide a baseline for future studies on the roles of specific molecules in renal development.

Analysis of SiC fibres and composites using raman microscopy

The application of Raman spectroscopy in the analysis of the microstructure of SCS-6 silicon carbide fibres using a Renishaw Raman microscope is described. It is demonstrated that the technique allows a detailed study to be made of the point-to-point variation in microstructure across a fibre section. It has been possible to monitor the variation of the concentration of SiC and carbon in the fibre microstructure and to detect differences in the forms of carbon present. It is also shown that Raman spectroscopy can be used to follow the micromechanics of both the deformation of silicon carbide fibres and of the fibres within a model composite. Well-defined Raman spectra have been obtained from a variety of Nicalon and Tyranno fibres and the positions of the Raman bands shown to shift on the application of stress or strain. From such stress-induced Raman band shifts, the point-to-point variation of axial fibre stress or strain along an individual fibre in an epoxy matrix can be determined. An example is given of the use of the technique to map the distributions of axial fibre strain in a Nicalon/epoxy fragmentation test specimen and to model the failure processes at the fibre/matrix interface.

Lactobacillus GG in the prevention of antibiotic-associated diarrhea in children

OBJECTIVE

The objective of this study was to determine the efficacy of Lactobacillus casei sps. rhamnosus (Lactobacillus GG) (LGG) in reducing the incidence of antibiotic-associated diarrhea when coadministered with an oral antibiotic in children with acute infectious disorders.

STUDY DESIGN

Two hundred two children between 6 months and 10 years of age were enrolled; 188 completed all phases of the protocol. LGG, 1 x 10(10) - 2 x 10(10) colony forming units per day, or comparable placebo was administered in a double-blind randomized trial to children receiving oral antibiotic therapy in an outpatient setting. The primary caregiver was questioned every 3 days regarding the incidence of gastrointestinal symptoms, predominantly stool frequency and consistency, through telephone contact by blinded investigators.

RESULTS

Twenty-five placebo-treated but only 7 LGG-treated patients had diarrhea as defined by liquid stools numbering 2 or greater per day. Lactobacillus GG overall significantly reduced stool frequency and increased stool consistency during antibiotic therapy by the tenth day compared with the placebo group.

CONCLUSION

Lactobacillus GG reduces the incidence of antibiotic-associated diarrhea in children treated with oral antibiotics for common childhood infections.

A systematic review of foot ulcer in patients with Type 2 diabetes mellitus. I: prevention

AIM

To evaluate the role of preventative strategies in reducing foot ulcers in patients with Type 2 diabetes mellitus, both in the general population and those identified to be at a raised risk.

METHOD

A systematic review of interventions to prevent diabetic foot ulcers.

RESULTS

Available studies are generally unsatisfactory in their ability to answer the important questions relating to prevention. However, where people with diabetes receive well-organized and regular care with rapid referral to appropriate specialist multidisciplinary teams when problems (or their precursors) occur, ulcer morbidity can be substantially reduced.

CONCLUSION

Foot ulcers are common in people with diabetes and are costly in terms of both patient morbidity and the use of healthcare resources. Although it is nearly a decade since the St Vincent Declaration called for a marked reduction in morbidity to be achieved through better patient management, available evidence suggests that the process of care in Britain is still very variable in quality. Foot care for people with diabetes must be organized to provide monitoring, education and referral in a manner acceptable to patients and realistic for local healthcare providers.

New options for pumps and tubes: progress in enteral feeding techniques and devices

In the past, blenderized tube feeds prepared in the hospital kitchen were delivered by bolus or gravity at intervals of 4-6 h. These methods lack consistent steady flow and many times are not a safe mode of delivery for those at risk of vomiting and aspiration, and cause more patient discomfort than nutritional benefit. More recently, enteral feeding administration techniques and devices have been developed for the delivery of commercially prepared enteral formulas designed for specific disease states. These technological advances have improved enteral feeding practices.

The effect of solvents on spider silk studied by mechanical testing and single-fibre Raman spectroscopy

We used well-defined, fluorescence-free Raman spectra of single silk fibres to study silk ultrastructure. Major ampullate (MA) silk was reeled from the Araneus diadematus spider under controlled conditions. With a custom-built stress-strain gauge, we examined the mechanical properties of this silk both before and after supercontraction in a range of solvents. The solvents were found to modify the material properties considerably. We suggest that the solvents with their different polarities affect different regions of the silk's composite microstructure, in particular the conformation of the molecular chains.

Continuous infusion ceftazidime in intensive care: a randomized controlled trial

We randomized 18 critically ill patients to receive ceftazidime 6 g/day by continuous infusion or bolus dosing (2 g 8 hourly), each with a loading dose of 12 mg/kg ceftazidime. During the first 8 h, plasma ceftazidime concentration fell below 40 mg/L in only one patient (trough 38 mg/L) from the infusion group, compared with eight from the bolus group (2-33 mg/L) for periods ranging from 73 to 369 min. Thereafter all infusion patients remained above 40 mg/L for 40 h of study versus 20-30% of bolus patients. The pharmacokinetic and pharmacodynamic characteristics of ceftazidime suggest that continuous infusions should be clinically investigated in outcome studies.

A comparison of the Hamamatsu NIRO 500 and the INVOS 3100 near-infrared spectrophotometers

Near-infrared spectroscopy is a technique used for non-invasive measurement of cerebral oxygenation and a number of commercial devices are currently available for use. We compared measurements of cerebral oxygenation made with two near-infrared spectrophotometers--the Somanetics Invos 3100 cerebral oximeter and the Hamamatsu NIRO-500 near-infrared spectrophotometer. Hypoxia was induced in six healthy male volunteers with and without occlusion of scalp blood flow. Oxygen saturation, end-tidal carbon dioxide tension, regional cerebral oxygen saturation, change in regional cerebral oxyhaemoglobin concentration and change in regional cerebral total haemoglobin concentration were measured. The INVOS 3100 displays cerebral oxygen saturation directly. The NIRO-500 displays change in total haemoglobin concentration and oxyhaemoglobin concentration, and the cerebral oxygen saturation was calculated offline. Statistical analysis disproved the assumption that the INVOS 3100 and the NIRO-500 were measuring the same changes in cerebral oxygenation. Neither machine can be confirmed for reliability against a gold standard and operational difficulties mean that neither can be recommended for routine clinical use.

Use of probiotics in childhood gastrointestinal disorders

Probiotics appear to be useful in the prevention or treatment of several gastrointestinal disorders, including infectious diarrhea, antibiotic diarrhea, and traveler's diarrhea. Results of preliminary human and animal studies suggest that patients with inflammatory diseases, and even irritable bowel syndrome, may benefit from probiotic therapy. Probiotics represent an exciting therapeutic advance, although much investigation must be undertaken before their role in gastroenterology is clearly delineated. Questions related to probiotic origin, survivability, and adherence are all important considerations for further study. More important, each probiotic proposed must be studied individually and extensively to determine its efficacy and safety in each disorder for which its use may be considered.

Problem of amputations in patients with newly diagnosed diabetes mellitus

A reduction of 50% or more in diabetes-related amputations is a primary target of the St Vincent Declaration. This is thought to be achievable because both primary and secondary preventative healthcare strategies are effective in reducing the incidence of diabetic foot ulceration and progression to amputation. Unfortunately there is a group who cannot benefit from preventative health care, that is, newly diagnosed diabetic patients with already established severe complications. Using our population-based district diabetes information system we investigated, during the period 1 January 1992 to 31 December 96, the incidence and prevalence of lower extremity amputations (LEAs) and the proportion occurring in patients newly or recently diagnosed as having diabetes. Seventy-nine diabetic patients (59 male, 20 female) were recorded as having had 94 LEAs, the incidence of diabetes-related LEA being 475 per 100,000 diabetic patient-years. Of these LEAs 16 (20.2%) were performed within 1 year of diabetes being diagnosed. This study highlights an appreciable and previously unrecognized problem: patients presenting with established complications of diabetes who cannot benefit from secondary preventative healthcare. These patients pose a potential obstacle to achieving targets for reductions in diabetes-related amputations.

Treatment strategies for small bowel bacterial overgrowth in short bowel syndrome

BACKGROUND

Small bowel bacterial overgrowth is a common complication of short bowel syndrome, and although it is often controlled with antimicrobial therapy, alternative strategies may occasionally be needed.

METHODS

Six patients with bacterial overgrowth are described, who did not respond to antimicrobial therapy and required additional medical or surgical measures to control the overgrowth.

RESULTS

Recalcitrant bacterial overgrowth was successfully treated with periodic small bowel irrigation with a balanced hypertonic electrolyte solution, colonic flushes, encouraging frequent stooling, intestinal lengthening procedure, or probiotic therapy with Lactobacillus plantarum 299V and Lactobacillus GG.

CONCLUSIONS

Small bowel bacterial overgrowth should be aggressively evaluated in patients with short bowel syndrome who are not progressing in a normal manner. Inadequate or incomplete response to antibiotic therapy is common, and several additional treatment possibilities are available.

Increasing oral fluids in chronic constipation in children

Increasing the amount and type of fluid intake in children with simple constipation remains a common intervention recommended by both the medical profession and lay consumers. Efforts to increase overall water intake and/or high osmolarity liquid intake have no research or physiological basis that would result in softer and/or more frequent stools. The purpose of this project was to identify whether an effect on stooling characteristics would be noted with a concerted effort to increase liquid intake.

Influence of bacterial overgrowth and intestinal inflammation on duration of parenteral nutrition in children with short bowel syndrome

OBJECTIVES

Massive intestinal resection results in short bowel syndrome and necessitates prolonged parenteral feeding. The purpose of this work was to assess the impact of late complications of short bowel syndrome, including intestinal bacterial overgrowth and enterocolitis, on the duration of parenteral nutrition (PN) in comparison with factors evident in the neonatal period.

METHODS

Retrospective chart review.

RESULTS

Of 49 children, 42 were weaned from parenteral nutrition after a treatment course of 17 +/- 14 months. In these 42, postresection small intestinal length equaled 81 +/- 65 cm; 45% had an ileocecal valve. Small intestinal length in the seven children who were PN dependent was 31 +/- 30 cm (p < 0.05); none had an ileocecal valve (p < 0.05). Bacterial overgrowth occurred in all seven PN-dependent children and in 23 of 42 children eventually weaned from PN (p < 0.05). When bacterial overgrowth was identified before weaning (n = 12), the duration pf PN was 28 +/- 17 months, but when bacterial overgrowth was first identified only after weaning (n = 11), the duration of PN was 16 +/- 13 months (p < 0.05). Small intestinal inflammation correlated with bacterial overgrowth (r = 0.69). Those children with severe enteritis identified before weaning remained on the PN regimen for 36 +/- 15 months, in comparison with 21 +/- 14 months in those with mild enteritis and 13 +/- 11 months in those without inflammation (p < 0.02).

CONCLUSIONS

Although the length of small intestine remaining after resection is the best immediate predictor of final success in terminating PN in children with short bowel syndrome, PN is prolonged by bacterial overgrowth and associated enteritis in those who will ultimately be weaned.

Intermittent bolus dosing of ceftazidime in critically ill patients

Ceftazidime is frequently used in critically ill patients, particularly for the treatment of Pseudomonas aeruginosa infections. The recommended dosing regimen is based on pharmacokinetic data obtained in healthy volunteers and may not be appropriate in the critically ill. We administered ceftazidime in the maximum recommended dose (2 g i.v. every 8 h) to ten critically ill patients with normal plasma creatinine. Eighteen arterial blood samples were taken from each patient over the first 8 h for measurement of ceftazidime concentrations and subsequent compartmental pharmacokinetic analysis. An additional trough sample was taken from each patient on day 3. Although mean pharmacokinetic variables did not differ from previously reported data in normal volunteers there was wide variability in plasma drug concentrations. Three of our patients had plasma ceftazidime concentrations less than the MIC for P. aeruginosa (8 mg/L) and nine had concentrations less than 5 x MIC, which has been recommended to ensure efficacy. On day 3 trough ceftazidime concentrations were less than the MIC in four out of the seven patients in whom measurements were made and less than 5 x MIC in the remaining three. There was no clinical predictor of which patients would have low plasma concentrations. Our results show that plasma concentrations of ceftazidime are very variable when the recommended intermittent bolus dosing regimen is used and may result in inadequate plasma concentrations of drug in critical infections. This may result in treatment failure and the emergence of antibiotic resistance. A loading dose followed by continuous infusion should overcome these problems but this awaits in-vivo evaluation.

Gastric tonometry and prediction of outcome in the critically ill. Arterial to intramucosal pH gradient and carbon dioxide gradient

Splanchnic ischaemia is thought to be of central importance in the development of multi-organ failure and hence death in critically ill patients. It has been suggested that the arterial to gastric intramucosal pH gradient and the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood are more sensitive markers of splanchnic ischaemia than gastric intramucosal pH itself and thus should be predictors of mortality in the critically ill. We studied 62 critically ill patients within 6 h of admission to the intensive care unit and found no significant difference at 0, 12 or 24 h after admission to the study in either the arterial to gastric intramucosal pH gradient or the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood between survivors and nonsurvivors. We conclude that in contrast to gastric intramucosal pH neither the arterial to gastric intramucosal pH gradient nor the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood distinguish survivors from nonsurvivors.

Development of the Vulnerability Scale

Developing a new data collection scale is a time- and labor-intensive process. Initially, the items may be developed from a review of the appropriate literature, clinical expertise of the developer, in-depth interviewing of potential subjects, or any combination of these techniques. Next, evidence of the validity (content-related, construct-related, and criterion-related), internal consistency reliability, and reliability of the scale must be established. The new scale may be administered to one or two small samples (pilot studies) before it is ready for use with a larger group. Gathering evidence regarding the scale's validity and reliability with different groups and consequent revision are ongoing processes. In this article, the authors describe how this process was followed in developing the Vulnerability Scale.