A remedial intervention linked to a formative assessment is effective in terms of improving student performance in subsequent degree examinations

BACKGROUND

Intervention may help weaker medical students improve their performance. However, the effectiveness of remedial intervention is inconclusive due to small sample sizes in previous studies. We asked: is remedial intervention linked to a formative assessment effective in terms of improving student performance in subsequent degree examinations?

METHODS

This was a retrospective, observational study of anonymous databases of student assessment outcomes. Data were analysed for students due to graduate in the years 2005-2009 (n = 909). Exam performance was compared for students who received remediation versus those who did not. The main outcome measure was summative degree examination marks.

RESULTS

After adjusting for cohort, gender, overseas versus home funding, previous degree and previous performance in the corresponding baseline third year summative exam, students receiving a remedial intervention (after poor performance on a formative objective structured clinical examination and written exams mid-fourth year) were significantly more likely to obtain an improved mark on end-of-fourth year summative written (p = 0.005) and OSCE (p = 0.001) exams compared to those students who did not receive remediation.

CONCLUSION

A remedial intervention linked to poor assessment performance predicted improved performance in later examination. There is a need for prospective studies in order to identify the effective components of remedial interventions.

Laparoscopic decapsulation of congenital splenic cysts: a step forward in splenic preservation

PURPOSE

The aim of this study was to evaluate the role of laparoscopic decapsulation in the management of congenital splenic cysts in children.

METHODS

Patients who presented over the last decade with congenital splenic cysts and were treated with laparoscopic decapsulation were reviewed retrospectively. The authors performed 4 procedures in 3 patients aged 10, 11 (and later 13), and 13 years. In all cases there was progressive enlargement of a single cyst, which lay in the upper pole of the spleen in 3 instances and in the lower pole in the fourth. Pneumoperitoneum was induced using the Veress needle technique, and 3 or 4 ports were utilized. Cysts were aspirated initially before marsupialization with excision of around two thirds of the cyst wall. Both endoshears and the harmonic scalpel were used with good hemostatic effect.

RESULTS

All patients had a good outcome with cyst resolution on long-term follow-up using serial ultrasound scanning. The first patient (in 1993) remained 3 days as an in patient postoperatively, and the others stayed overnight only. One patient had a new cyst near the first 30 months after the initial procedure. This again was dealt with laparoscopically, with patient discharge the following day. There were no complications in the short or long term. Histology in all cases confirmed a simple epithelial cyst. Median follow-up was 2 years (range, 6 months to 8 years).

CONCLUSIONS

Our experience shows that laparoscopic decapsulation is an effective means of managing congenital splenic cysts and that both harmonic scalpel and endoshears are satisfactory dissecting instruments. Extensive marsupialization is probably unnecessary in these larger cysts, because long-term follow-up has shown no increased risk of recurrence after leaving a significant proportion of the cyst wall behind. This approach helps avoid major surgery in these cases.

Is there a role for balloon dilatation of pelvi-ureteric obstruction in children?

PURPOSE

The aim of this study was to examine the effectiveness of balloon dilatation with double J stenting in the management of children with pelvi-ureteric junction (PUJ) obstruction.

METHODS

A retrospective study of a 4-year experience of PUJ balloon dilatation in children was conducted in a single unit. Information was collected on patient demographics, clinical presentation, the procedure of balloon dilatation, renal function, and antero-posterior renal pelvis diameter both pre- and postoperatively.

RESULTS

There were 10 patients with a median age of 12.5 years (range, 21 months to 15 years). Four cases presented with ipsilateral flank pain, 3 with urinary tract infection, and 3 were discovered incidentally. Retrograde dilation was performed in all cases. Dilation was considered an initial success in 8 of 10 cases, and 1 patient deteriorated after 17 months. Double J stents were placed in all cases and remained in situ for a median of 7.5 weeks (range, 7 to 8.5). Median in-hospital stay was 2 days. Median follow-up was 34 months (range, 7 to 48). Ipsilateral renal excretion times (on MAG III isotope scanning) improved markedly from a median of 84 minutes (range 13 to 200) preoperatively to 7 minutes (range, 1 to 200) at 3 months and 7 minutes (range 1 to 113) at 12 months postoperatively. Median pelvic AP diameter reduced from 30 mm (range 22 to 74) to 16 mm (range, 8 to 36) at 2 months and 10 mm (range, 4 to 41) at 7 months. There were 2 immediate failed procedures, both occurred in patients who went on to open pyeloplasty and were found to have aberrant renal vessels causing extrinsic PUJ compression. One child deteriorated between 10 and 17 months and went on to open pyeloplasty. Twenty-two patients underwent open pyeloplasty in the unit during the same time period with a 95% success rate. Median stay was longer at 5 days and median age younger at 22 months (range, 6 weeks to 13 years).

CONCLUSION

Balloon dilatation is a viable option in the management of PUJ obstruction, carrying minimal morbidity in experienced hands.

In vivo exposure to bicarbonate/lactate- and bicarbonate-buffered peritoneal dialysis fluids improves ex vivo peritoneal macrophage function

The impact on peritoneal macrophage (PMO) function of acidic lactate-buffered (Lac-PDF [PD4]; 40 mmol/L of lactate; pH 5.2) and neutral-pH, bicarbonate-buffered (TB; 38 mmol/L of bicarbonate; pH 7. 3) and bicarbonate/lactate-buffered (TBL; 25 mmol/L of bicarbonate/15 mmol/L of lactate; pH 7.3) peritoneal dialysis fluids (PDFs) was compared during a study of continuous therapy with PD4, TB, or TBL. During a run-in phase of 6 weeks when all patients (n = 15) were treated with their regular dialysis regimen with Lac-PDF, median PMO tumor necrosis factor alpha (TNFalpha) release values were 203.6, 89.9, and 115.5 pg TNFalpha/10(6) PMO in the patients subsequently randomized to the PD4, TB, and TBL treatment groups, respectively. Median stimulated TNFalpha values (serum-treated zymosan [STZ], 10 microgram/mL) were 1,894.6, 567.3, and 554.5 pg TNFalpha/10(6) PMO in the same groups, respectively. During the trial phase of 12 weeks, when the three groups of patients (n = 5 per group) were randomized to continuous treatment with PD4, TB, or TBL, median constitutive TNFalpha release values were 204.7, 131.4, and 155.4 pg TNFalpha/10(6) PMO, respectively. Stimulated TNFalpha values (STZ, 10 microgram/mL) were 1,911, 1,832, and 1,378 pg TNFalpha/10(6) PMO in the same groups, respectively. Repeated-measures analysis of variance comparing the run-in phase with the trial phase showed that PMO TNFalpha release was significantly elevated in patients treated with both TB (P = 0.040) and TBL (P = 0.014) but not in patients treated with Lac-PDF (P = 0. 795). These data suggest that patients continuously exposed to bicarbonate- and bicarbonate/lactate-buffered PDFs might have better preserved PMO function and thus improved host defense status.

Macrophages and mesothelial cells in bacterial peritonitis

Research in recent years has examined the mechanisms underlying cellular host defence in the peritoneal cavity. These studies have established that the resident cells of the peritoneal cavity, the peritoneal macrophages (PM phi) and the mesothelial cells (HPMC) contribute to the initiation, amplification and resolution of peritoneal inflammation. Ex vivo measurements of intra-peritoneal inflammatory mediators during peritonitis has elucidated the time courses for the generation of proinflammatory, chemotactic and anti-inflammatory cytokines and have identified that their secretion occurs largely within the peritoneum. These studies provide evidence that both PM phi- and HPMC-derived mediators are directly involved in controlling inflammation. It has been widely accepted that resident PM phi form the first line of defence against peritoneal infection, a more contemporary view would suggest that the direct or indirect (via secreted pro-inflammatory cytokines) interaction between PM phi and HPMC is pivotal to the activation and subsequent amplification of the peritoneum's response to infection. Whilst the site of these interactions is unknown, considerable evidence suggests that it occurs on the surface of the mesothelium, where invading micro-organisms may colonize. In this respect Staphylococcal exoproducts can directly activate HPMC cytokine synthesis. Once the inflammatory response is initiated, recent evidence suggests, that mesothelial cells upon activation by PM phi-derived IL-1 beta and TNF-alpha, are capable of amplifying inflammation and generating signals (via the creation of a gradient of chemotactic cytokines, IL-8, MCP-1 and RANTES) for the recruitment of leukocytes into the peritoneum. This process is also facilitated via the cytokine driven up-regulation of adhesion molecule expression (ICAM-1 and VCAM-1) on HPMC. Much less is understood about the mechanisms by which inflammation is resolved, although the secretion of anti-inflammatory molecules (IL-6, IL-1ra and soluble TNF-p55/75) by receptors by PM phi and HPMC may be important in the process. The existence of a peritoneal cytokine network controlling inflammation is now well established, within this the interaction of PM phi and HPMC appears to play a pivotal role in the hosts response to peritoneal infection.

Staphylococcal exoproducts down-regulate cyclooxygenase 1 and 2 in peritoneal macrophages

Peritoneal macrophages (PMOs) are important components of the host defense against microbial infection in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Incubation of human PMOs with cell-free supernatant (BFS), prepared from Staphylococcus aureus, inhibited prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) production. Slot-blot analysis of cyclooxygenase-1 (Cox-1) and Cox-2 demonstrated a decrease in both Cox-1 (29%) and, to a greater extent, Cox-2 (65%) protein expression after BFS stimulation. When competitive polymerase chain reaction (PCR) was used, the peak levels of Cox-1 and Cox-2 messenger ribonucleic acid (mRNA) in unstimulated PMOs were 0.304+/-0.13 pmol/L and 9.61+/-2.84 pmol/L (mean+/-SEM, n = 3), respectively. After exposure of samples to BFS for 30 minutes, the level of Cox-2 mRNA was reduced to 0.59+/-0.449 pmol/L (16-fold reduction, p < 0.05), and the level of Cox-1 mRNA was reduced to 0.02+/-0.002 pmol/L (15-fold reduction, p < 0.05). In contrast, these same PMOs showed an increased expression of IL-6 mRNA and increased secretion of IL-6 protein. These results indicate that prostaglandin production in PMOs is regulated by alterations in both immunoreactive Cox-1 and Cox-2. The down-regulation of Cox metabolism in these cells is primarily related to the delayed and depressed increase in the Cox-2 gene product.

Macrophages and mesothelial cells in bacterial peritonitis

Research in recent years has examined the mechanisms underlying cellular host defence in the peritoneal cavity. These studies have established that the resident cells of the peritoneal cavity, the peritoneal macrophages (PM phi) and the mesothelial cells (HPMC) contribute to the initiation, amplification and resolution of peritoneal inflammation. Ex vivo measurements of intra-peritoneal inflammatory mediators during peritonitis has elucidated the time courses for the generation of proinflammatory, chemotactic and anti-inflammatory cytokines and have identified that their secretion occurs largely within the peritoneum. These studies provide evidence that both PM phi- and HPMC-derived mediators are directly involved in controlling inflammation. It has been widely accepted that resident PM phi form the first line of defence against peritoneal infection, a more contemporary view would suggest that the direct or indirect (via secreted pro-inflammatory cytokines) interaction between PM phi and HPMC is pivotal to the activation and subsequent amplification of the peritoneum's response to infection. Whilst the site of these interactions is unknown, considerable evidence suggests that it occurs on the surface of the mesothelium, where invading micro-organisms may colonize. In this respect Staphylococcal exoproducts can directly activate HPMC cytokine synthesis. Once the inflammatory response is initiated, recent evidence suggests, that mesothelial cells upon activation by PM phi-derived IL-1 beta and TNF-alpha, are capable of amplifying inflammation and generating signals (via the creation of a gradient of chemotactic cytokines, IL-8, MCP-1 and RANTES) for the recruitment of leukocytes into the peritoneum. This process is also facilitated via the cytokine driven up-regulation of adhesion molecule expression (ICAM-1 and VCAM-1) on HPMC. Much less is understood about the mechanisms by which inflammation is resolved, although the secretion of anti-inflammatory molecules (IL-6, IL-1ra and soluble TNF-p55/75) by receptors by PM phi and HPMC may be important in the process. The existence of a peritoneal cytokine network controlling inflammation is now well established, within this the interaction of PM phi and HPMC appears to play a pivotal role in the hosts response to peritoneal infection.

The response of human peritoneal macrophages to stimulation with bacteria isolated from episodes of continuous ambulatory peritoneal dialysis-related peritonitis

The metabolism of arachidonic acid, by isolated peritoneal macrophages in response to stimulation with microorganisms isolated from continuous ambulatory peritoneal dialysis (CAPD) patients, is not specific to the individual strain but is determined by species. Isolates of Staphylococcus aureus (n = 7) and Staphylococcus epidermidis (n = 13) produced a significant increase in leukotriene B4 generation by peritoneal macrophages compared with unstimulated cells (P less than .001). The coincubation of peritoneal macrophages with gram-negative organisms (n = 3), however, did not result in an increase in leukotriene B4 synthesis. In contrast, all the organisms tested significantly inhibited the formation of prostaglandin E2 and thromboxane B2 but the degree of inhibition was species dependent. The above results were reproduced using bacteria-free supernatants, indicating that the interaction was dependent on a secreted bacterial product. Thus in response to certain bacterial species, the recruitment of neutrophils may be facilitated by the generation of leukotriene B4 from peritoneal macrophages. In addition, the reduction in synthesis of prostaglandin E2 may remove a regulatory effect that this metabolite has on the immune response.

Eicosanoid synthesis in human peritoneal macrophages stimulated with S. epidermidis

Peritoneal macrophages isolated from CAPD patients phagocytosed S. epidermidis in a time dependent manner. Coincident with a maximum phagocytic uptake of 56% by 12 hours, there was secretion of a significant amount of neutral protease (1.37 +/- 0.2 mg [3H]-casein degraded/10(6) cells, P = 0.05). In contrast to these delayed effects, coincubation of PMO with S. epidermidis resulted in a significant increase in both LTB4 and LTC4 synthesis above that of controls, with 6.33 +/- 1.20 ng LTB4/10(6) cells (P less than 0.01) and 2.06 +/- 0.68 ng LTC4/10(6) cells (P = 0.014) being generated by three hours. The generation of these lipoxygenase products was both time and dose dependent, and the rapid production and release of the potently chemotactic LTB4 is consistent with the observed clinical response, where a rapid influx of PMN into the peritoneal cavity occurs during episodes of peritonitis, while the generation of LTC4 may contribute to the hyperemia and interstitial edema. In contrast, although there was a time dependent rise in cyclooxygenase product generation by unstimulated cells, a dose dependent inhibition of synthesis was clearly demonstrated when cells were incubated with bacteria, with a mean 40% reduction in generation of PGE2 and a mean 34% reduction in TXB2 generation (P = 0.01 and P less than 0.025, respectively). It was demonstrated that the inhibition was not due to lack of available substrate and that the generation of eicosanoids was unrelated to phagocytosis, bacterial/PMO contact or bacterial surface characteristics. Instead, the observed effect of S. epidermidis on the PMO was attributable to a secreted bacterial product.

The assessment of relative surface hydrophobicity as a factor involved in the activation of human polymorphonuclear leukocytes by uropathogenic strains of Escherichia coli

The initiation of the respiratory burst and the degranulation of human polymorphonuclear leukocytes (PMN) in response to stimulation by uropathogenic strains of Escherichia coli is dependent on the expression of Type 1 fimbriae by those strains. These PMN responses correlate with an increasing tendency of the interacting E. coli strain to be retained on hydrophobic columns. The present work assessed the measurement of relative surface hydrophobicity in relation to PMN activation. Type 1 fimbriate organisms bound most readily to Octyl-Sepharose columns and were strongly agglutinated in the salt aggregation test. In contrast, the same organisms partitioned to the dextran-rich (hydrophilic) phase of aqueous two-polymer phase systems. Electron microscopic observation of the organisms eluted from the Octyl-Sepharose columns and of the organisms recovered from both phases of the aqueous two-phase systems demonstrated, however, that both Type 1 and P-fimbriate organisms were retained on the columns and partitioned into the dextran-rich phase as a consequence of their being fimbriate and failed to identify this as a major factor in the activation of PMN. In addition electron microscopy demonstrated that each P-fimbriate population had fewer organisms expressing fimbriae than did Type 1 fimbriate populations, confirming the importance of phase variation as a factor affecting the physicochemical characteristics of a bacterial population.

Variable expression of P fimbriae in Escherichia coli urinary tract infection

Fresh urinary isolates were examined by immunofluorescence with polyclonal rabbit antibodies against type 1 and P fimbriae. This procedure showed P-fimbriate Escherichia coli in 22 of 24 samples from patients with asymptomatic bacteriuria, 24 of 26 samples from patients with cystitis, and 6 of 6 samples from patients with pyelonephritis. Type 1 fimbriae were expressed by less than 40% of isolates in all three groups. There was no relation between the presence of symptoms or the site of infection and fimbrial expression, of P or type 1, by bacteria adherent to freshly isolated uroepithelial cells.