Recognizing spatial patterns: a noisy exemplar approach

Models of categorization typically rely on the use of stimuli composed of well-defined dimensions (e.g., Ashby & Maddox (1998) in Choice, decision, and measurement: Essays in honor of R. Duncan Luce, p. 251-301, Mahwah, NJ: Erlbaum). We apply a similar approach to the analysis of recognition memory. Using a version of short-term recognition paradigm (Sternberg, Science 153 (1966) 652), we asked whether NEMO Sternberg's, a noisy exemplar summed-similarity model, could account for variation in mean performance on individual trials. NEMO provided a very good overall fit to recognition data from three experiments. However, its failure to fit data for certain lists of stimuli suggested a revision of the summed-similarity assumption. Our model-based analysis showed that subjects used interitem similarity, in addition to probe-item similarity, as the basis for their decisions. This represents a major departure from existing recognition models that assume subjects' judgments depend exclusively on the summed similarity of the probe to the study items.     

Ocular perfusion abnormalities in diabetes

PURPOSE: To review the role of ocular perfusion in the pathophysiology of diabetic retinopathy, one of the leading causes of irreversible blindness in the industrialized world. METHODS: We carried out a Medline search of the literature published in English or with English abstracts from 1966 to 2000 using various combinations of relevant key words. RESULTS: Hyperglycaemia leads to a wide variety of vascular abnormalities at the microvascular and macrovascular levels, including abnormal autoregulation. CONCLUSION: Three major aspects of ocular perfusion in diabetic retinopathy require additional investigation. Firstly, the precise mechanisms that link elevated glucose to dysfunction of retinal vascular cells need to be identified. Secondly, those factors that lead to both capillary dropout and to angiogenesis, twin processes that are linked to tissue hypoxia and lead to excess perfusion, increased risk of extravascular leakage and frank haemorrhage, must be carefully delineated. Finally, once specific knowledge of disease fundamentals has been amassed, tests of therapies to reverse or prevent these pathological processes can move forward.     

Routine postoperative imaging is important after ureteroscopic stone manipulation

PURPOSE: Improved fiber optics and advanced intracorporeal lithotripsy devices have significantly decreased the incidence of complications during ureteroscopic procedures. Despite recent reports suggesting that radiographic imaging may not be necessary in all individuals after routine ureteroscopy silent obstruction may develop in some, ultimately resulting in renal damage. We determined the incidence of postoperative silent obstruction at our institution and assessed the need for routine functional radiographic studies after ureteroscopy. MATERIALS AND METHODS: We retrospectively reviewed the charts of 320 patients who underwent a total of 459 ureteroscopic procedures for renal or ureteral calculi in a 3-year period. Complete followup with imaging was available for 241 patients (75%). Average patient age was 47.2 years. The variables of interest reviewed included preoperative pain, preoperative obstruction, targeted calculous site, stone-free rate, postoperative pain and postoperative obstruction. Mean followup was 5.4 months (range 2 to 43). RESULTS: A total of 241 patients with complete followup were identified in this analysis. Preoperative pain was present in 202 patients (84%) and 168 (70%) had preoperative obstruction. Overall targeted calculous clearance was successful in 73% of the patients and an additional 15.8% had residual fragments less than 4 mm. The renal, proximal or mid and distal ureteral stone-free rate was 32.1%, 81.9% and 90.5%, while in an additional 46.4%, 6.3% and 6.7% of cases, respectively, residual fragments were less than 4 mm. Of the 241 patients 30 (12.3%) had obstruction postoperatively due to residual stone in 25 (83.3%), stricture in 3 (10%), edema of the ureteral orifice in 1 (3.3%) and a retained encrusted stent in 1 (3.3%). Postoperatively obstruction correlated with postoperative pain in 23 of the 30 patients (76.7%). Pain was present postoperatively in 30 of the 211 patients (14%) without evidence of ureteral obstruction postoperatively. However, silent obstruction developed in 7 patients (23.3%) or 2.9% of the total cohort. All 7 patients underwent secondary ureteroscopy to alleviate obstruction. A single patient ultimately received chronic hemodialysis for renal failure, 1 was lost to followup and in 5 there was documented successful resolution of the cause of obstruction. CONCLUSIONS: Our analysis suggests that silent obstruction remains a potentially significant complication after stone management. Relying on postoperative pain to determine the necessity of postoperative imaging places patients at risk for progressive renal failure due to unrecognized obstruction. Therefore, we recommend that imaging of the collecting system should be performed by excretory urography, spiral computerized tomography or ultrasound within 3 months after routine ureteroscopic stone treatment to avoid the potential complications of unrecognized ureteral obstruction.     

Perianal Crohn disease: a new scoring system to evaluate and predict outcome of surgical intervention

BACKGROUND: Conventional Crohn disease activity indices do not reflect perianal disease activity or allow prognostic implications from surgery. HYPOTHESIS: A new scoring system, based on the patient's disease history and physical examination findings, will allow more accurate use of surgical intervention for perianal Crohn disease. METHODS: A standardized scoring questionnaire was developed and applied to a consecutive group of patients before surgical treatment of perianal Crohn disease. The scoring system included abscess, fistula, ulcer and fissure, stenosis, incontinence, and concomitant disease. Weighted factors included acuity vs chronicity, de novo vs recurrent disease, and concomitant intestinal disease. The scoring system was validated against the surgical outcome, which was classified as poor, satisfactory, or good. RESULTS: Twenty-eight patients with Crohn disease who underwent 33 surgical procedures had a mean score of 16.5 (range, 3-37; possible range, 0-55). Using the Spearman nonparametric correlation test, the scoring system was accurate in predicting the outcome of surgical intervention (correlation coefficient, 0.78, 95% confidence interval, 0.57-0.89; P<.001) at mean follow-up of 20.8 months (range, 6-40 months). Correlation was further validated using a linear regression model (r = 0.75, slope best-fit value, 3.8; 95% confidence interval, 2.46-5.14; P<.001). All patients with a score of 10 or less had a good outcome, whereas all those with a score of 20 or greater had a poor outcome. CONCLUSIONS: The proposed scoring system correlated well with the short-term outcome of surgical intervention in patients with perianal Crohn disease and allowed prediction of surgical success. Ultimately, it may be possible to alter therapy based on preoperative prediction of the expected postoperative outcome.     

Effects of guided written disclosure of stressful experiences on clinic visits and symptoms in frequent clinic attenders

BACKGROUND: Psychosocial variables such as major stressful life events/daily stressful events have been associated with health care utilization. OBJECTIVE: Our aim was to examine the effects of a guided disclosure protocol (GDP) of past traumas on symptoms and clinic visits among frequent clinic attenders. METHODS: Forty-one frequent clinic attenders (> or =2 visits/3 months) took part. Patients were randomly assigned individually to either a casual content writing control group (n = 19) or a trauma content writing experimental GDP group (n = 22). GDP patients wrote about an upsetting event chronologically (day 1), verbally described their thoughts and feelings and described the event's impact on life (day 2), and finally wrote about their current perspective on and future coping with the event (day 3). Three months later, patients were reassessed blindly for symptoms and clinic visits, and an average of 15 months later they were assessed blindly for clinic visits again. RESULTS: Compared with controls, GDP patients reported lower symptom levels at 3 months (2.3 versus 5.2), and made fewer clinic visits during the 3 (1.3 versus 3.0) and 15 month (5.1 versus 9.7) follow-ups. The percentage of GDP patients making > or =10 visits during the 15 month follow-up was smaller (10%) than among controls (33%). CONCLUSIONS: The findings extend previous findings to frequent clinic users, using a new form of written disclosure aimed at shifting trauma from implicit to explicit memory. The GDP may be an inexpensive additional intervention in primary care for reducing symptoms and clinic visits among frequent clinic users.     

Priming summation in the cerebral hemispheres: evidence from semantically convergent and semantically divergent primes

The ability to activate and to maintain a large and relatively undifferentiated semantic field has been thought to be an important component of lexical semantic processing by the right hemisphere (RH). An implication of this unique propensity of the RH was examined in the present study that included two divided visual field priming experiments with SOAs of 800 and 2500 ms. The experiments investigated the ability of the RH and the left hemisphere (LH) to summate activation from multiple primes followed by a laterally presented ambiguous target word. The priming words either converged onto the same semantic representation (i.e. all three words related to either the dominant or to the subordinate meaning of the target) or diverged onto distinct semantic representations (i.e. two words related to the dominant and one to the subordinate meaning of the target, or vice versa). Results indicated that for either an 800 or 2500 ms stimulus onset asynchrony (SOA) the LH benefited most from three semantically convergent primes that converged onto the dominant meaning of the ambiguous target word. There was no facilitation when three subordinate primes preceded the target. When the primes diverged onto different meanings, there was significant facilitation for the 800 ms SOA only. In contrast, with an 800 ms SOA, the RH benefited only from semantically divergent primes, that diverged onto alternate meanings of the ambiguous target word. With a 2500 ms SOA, the RH benefited from all combinations of primes. The discussion focuses on the implications for language processing of the differences between the two hemispheres in the scope and temporal pattern of the multiple prime effect.     

Confusing exit gunshot wound –“Two for the price of one”

During the post-mortem examination of a 36-year-old shooting victim, two entrance gunshot wounds in the back and only one corresponding exit wound in the chest were detected. The likelihood of a retained fragmented or whole bullet, or an embolic phenomenon was eliminated by full body x-ray examination. The only remaining plausible explanation was that the two bullet tracts had converged within the thorax, eventually exiting through a common exit wound. Dissection of the projectiles’ path confirmed this unusual phenomenon. Autopsy techniques for gunshot wound cases are discussed. Received: 25 May 2001 / Accepted: 20 August 2001     

玻璃体内注射曲安奈德治疗视网膜中央静脉阻塞引起的黄斑水肿

目的：探讨玻璃体内注射丙酮化曲安奈德用于治疗视网膜中央静脉阻塞（CRVO）引起黄斑水肿的安全性和有效性。方法：在Wisconsin大学和Bascom Palmer眼科研究所．对13例（13只眼）连续的CRVO引起黄斑水肿的患者应用玻璃体内注射丙酮化曲安奈德（4mg）治疗．回顾研究其病历记录。每次玻璃体内注射时应用27G或30G针头通过睫状体平坦部注射。主要结果测量：Snellen视力的变化、黄斑水肿的临床表现、应用光学相干断层扫描仪（OCT）测量中心凹的增厚以及并发症的出现频率。结果：13例患者的平均年龄为67岁（四分位数间距为57—77岁）．注射前症状的平均持续时间为8个月（四分位数间距为4—9个月）。患眼在初诊时的平均视力为20／500．在6个月随诊检查时的平均视力为20／1踟。所有13例患者都完成了6个月的随诊检查。非缺血型CRVO患眼（n=5）的视力有显著的提高．而缺血型CRVO患眼（n=8）没有显著的视力提高。患者没有出现视力下降。初诊时OCT测量的平均中心凹厚度为590μm（视网膜增厚=416μm）。12例患者在1个月随诊检查时OCT测量的平均中心凹厚度为212pm（视网膜增厚=38μm）。13例患者在3个月随诊检查时OCT测量的平均中心凹厚度为193μm（视网膜增厚=19μm）。在3和6个月随诊检查之间．4例患者的黄斑水肿复发．其中3例患者再次接受了曲安奈德的注射。这3例患者中的2例经过再次治疗视力提高。在6个月随诊检查时．13例患者OCT测量的平均中心凹厚度为281μm（视网膜增厚=107μm）。没有发生视网膜脱离或眼内炎等并发症。1例患者出现了眼压的升高．应用2种房水生成抑制剂治疗得以控制。结论：在部分CRVO引起黄斑水肿的患者中．玻璃体内注射曲安奈德可能是一种有效的治疗方法。与缺血型CRVO患者相比．非缺血型CRVO患者可以获得更令人满意的效果。部分患者可能需要重复治疗。在本组患者中未发现严重的并发症。     

Idiopathic hypercalciuria of childhood: 4- to 11-year outcome

Apart from a minority with urolithiasis, the majority of children diagnosed with idiopathic hypercalciuria present with macro- or microhematuria, abdominal or back pain, or voiding symptoms. With dietary and pharmacological interventions, most such children become asymptomatic and are lost to follow-up, hence their long-term outcome is unclear. In the present study, we evaluated the status of 14 males and 19 females aged 8-17 years (mean 11.9 years, median 11.2 years) 4-11 years (mean 6.9 years, median 6.5 years) after the initial diagnosis of idiopathic hypercalciuria not associated with urolithiasis. A questionnaire was answered and two random urine samples provided 3-4 weeks apart were analyzed for calcium (Ca), sodium (Na), potassium (K), and creatinine (Cr). Urine Ca/Cr ratio > or =20.21 (mg/mg) was defined as hypercalciuria. At the time of the study none were under follow-up, although 7 children were still exhibiting voiding symptoms. No child developed clinical urolithiasis. Based on the first urine specimen, 16 of the 33 (48.4%) were hypercalciuric. Their 2nd urinalysis showed persistent hypercalciuria in 8 and normocalciuria in 8. Urine Na/K ratio (mEq/mEq) decreased in the latter 8 from 5.08+/-2.67 to 3.03+/-2.23 (P<0.05). Of the 17 initially normocalciuric children, 5 did not submit a 2nd specimen, 11 remained normocalciuric, and 1 became hypercalciuric with an increase in urine Na/K ratio. Twenty-three children (all 8 persistently and 9 intermittently hypercalciuric plus 6 normocalciuric) were studied by ultrasonography. Only in 1 asymptomatic persistently hypercalciuric child was a single small renal calcification noted. Introduction of a low-Na/high-K diet in 7 persistently hypercalciuric children resulted in a decrease in UNa/K ratio from 7.34+/-2.15 to 4.14+/-3.09 (P<0.01) and UCa/Cr ratio from 0.25+/-0.04 to 0.13+/-0.03 (P<0.01). We conclude that even though over time most hypercalciuric children become asymptomatic, many remain hypercalciuric. Further follow-up is required to ascertain whether these children are at risk of developing kidney stones. If they are at risk then long-term compliance with a low-Na/high-K diet might be beneficial, as it can normalize calciuria in the majority of these children.