The representation of Kanizsa illusory contours in the monkey inferior temporal cortex.

Stimulus reduction is an effective way to study visual performance. Cues such as surface characteristics, colour and inner lines can be removed from stimuli, revealing how the change affects recognition and neural processing. An extreme reduction is the removal of the very stimulus, defining it with illusory lines. Perceived boundaries without physical differences between shape and background are called illusory (or subjective) contours. Illusory and real contours activate early stages of the macaque visual pathway in similar ways. However, data relating to the processing of illusory contours in higher visual areas are scarce. We recently reported how illusory contours based on abutting-line gratings affect neurones in the monkey inferotemporal cortex, an area essential for object and shape vision. We now present data on how inferotemporal cortical neurones of monkeys react to another type of shapes, the Kanizsa figures. A set of line drawings, silhouettes, their illusory contour-based counterparts, and control shapes have been presented to awake, fixating rhesus monkeys while single-cell activity was recorded in the anterior part of the inferotemporal cortex. Most of the recorded neurones were responsive and selective to shapes presented as illusory contours. Shape selectivity was proved to be different for line drawings and illusory contours, and also for silhouettes and illusory contours. Neuronal response latencies for Kanizsa figures were significantly longer than those for line drawings and silhouettes. These results reveal differences in processing for Kanizsa figures and shapes having real contours in the monkey inferotemporal cortex.

[Ethical aspects of parent-adolescent conflicts: about dignity]. / Repères éthiques et conflits adolescents-parents: de la dignité.

The work in Psychiatry of children and adolescents at the general hospital in paediatric and emergency services--where we have to meet any kind of children and adolescents, either hospitalized or only consulting--makes us discover clinical situations in which we must consider the whole life context of those young patients. Our experience shows that, within the problems and conflicts of the adolescent period, ethical questions concerning beliefs, values, ideals, hopes and prohibitions ... are, in paradoxal ways, underlying the constitution of the symptoms we are required to cure. If we respectfully pay attention to those aspects, we can help to increase choice possibilities, and we can contribute to overtake conflicts and difficulties. The ethical position for health workers could be to help the patient and his (her) family to regain their self esteem and dignity according to their own values and history.

Human immunodeficiency virus seroprevalence trends: five hospitals in south Georgia, 1993 through 1997.

BACKGROUND: Human immunodeficiency virus (HIV) seroprevalence surveys help determine the extent of HIV and the need for routine HIV counseling and testing. We sought to describe trends in five south Georgia hospitals and compare two protocols for conducting anonymous HIV surveys. METHODS: From 1993 to 1997, each hospital tested approximately 1,400 anonymous, leftover blood specimens per year. Two hospitals (C and E) tested all specimens, and three hospitals (A, B, and D) excluded blood known to be HIV-related. RESULTS: The mean HIV seroprevalence at hospitals C and E was between 2.0% and 2.3% each year. The mean HIV seroprevalence at hospitals A, B, and D increased from 0.5% to 1.0% during 1993 to 1995, then decreased to 0.3% in 1997. CONCLUSIONS: In hospitals C and E, the level of HIV disease was constant. In hospitals A, B, and D, the HIV seroprevalence decreased to 0.3%, suggesting that routine HIV counseling and testing is not currently needed in these hospitals. Hospitals should consider conducting periodic anonymous HIV seroprevalence surveys, sampling from all patients and distinguishing between specimens known to be HIV-related and those that are not.

An evaluation of the use of dried blood spots from newborn screening for monitoring the prevalence of cocaine use among childbearing women.

A collaborative March of Dimes study was designed to examine the utility of dried blood spot (DBS) materials routinely collected from newborns as a source for monitoring cocaine exposure and to assess the prevalence of cocaine use among childbearing women in Georgia. We used a modified urinary radioimmunoassay (RIA) to anonymously detect the cocaine metabolite benzoylecgonine (BE) in DBSs. Extensive efforts were undertaken to assure absolute nonlinkage of BE data to any individual. The positive results found by RIA were confirmed by a mass spectrometry (MS) method specifically developed to detect BE in DBSs. BE was measured in 23,141 DBSs collected during 2 months of routine newborn screening in Georgia. A good correlation was observed for RIA results versus MS results (r2 = 0.97). The estimated minimal statewide BE prevalence was 4.8 per 1000 childbearing women. We demonstrated that immunoassay testing for cocaine without confirmatory testing can yield falsely elevated prevalence rates. When proper confirmatory testing is done, DBSs are a valuable source for population-based monitoring of substance abuse among childbearing women.

Combined penetrating rectal and genitourinary injuries: a challenge in management.

The standard management of penetrating rectal trauma consists of perioperative antibiotics, a diverting colostomy, and presacral drainage. While providing optimal results in isolated rectal trauma, this management scheme is inadequate in combined penetrating rectal and genitourinary (GU) tract injuries. A review of more than 200 cases of penetrating rectal trauma from our institution over a 13-year period identified 17 concomitant GU tract injuries (13 bladder, three urethral, and one ureteral injury). Complications consisted of pelvic, suprapubic, or subphrenic abscesses in 3 of 17 cases (18%), rectovesical or rectourethral fistulae in 24%, chronic urinary tract infections in 18%, bladder stones in 12%, and the development of urethral strictures in 12% of patients. Factors implicated in their pathogenesis included failure to perform presacral drainage, distal rectal washout, and rectal wound repair; prolonged suprapubic drainage; and failure to separate the rectal and GU tract wounds. Careful debridement of all necrotic tissue, urinary and fecal diversion, tension-free wound closure with well-vascularized tissue, and adequate drainage and separation of the injured sites with well-vascularized tissue such as omentum should reduce the high incidence of rectourethral and rectovesical fistulae from combined rectal-GU tract trauma. Therapeutic recommendations for individualized treatment are presented.

Massive rectal bleeding from a Dieulafoy's type ulcer of the rectum: a review of this unusual disease.

Dieulafoy's ulcer is an uncommon lesion that usually presents with massive bleeding. Although it has been observed, for the most part, in the stomach, it has also been identified in the small bowel and colon. Both endoscopy and angiography have been used for diagnosis; however, endoscopy has had a high failure rate for localizing colonic disease during active bleeding. Treatment has been primarily surgical, but endoscopic coagulation and sclerotherapy have been recently employed. A 20-year-old male presented with massive lower gastrointestinal bleeding, which was found to be caused by a Dieulafoy's ulcer in the rectum. Observation of Dieulafoy's ulcer in the rectum has not been reported previously. Diagnosis was by rigid sigmoidoscopy. This lesion was treated by widely oversewing the vessel after endoscopic therapy failed. The etiology of this lesion is most likely congenital. Hemorrhage probably occurs as a result of mechanical damage of the mucosa, combined with erosion of the vessel by fecal flow. Unlike colonic Dieulafoy's ulcers, it should be possible to diagnose rectal lesions by rigid sigmoidoscopy. This diagnosis may be difficult with high rectal ulcers, and angiography may have to be employed. Endoscopic therapy failed here, as in other reports on colonic disease. Thus, we would recommend widely oversewing rectal lesions as the primary treatment. Resection should be reserved for cases that have failed this therapy.

General surgical problems requiring operation in postoperative vascular surgery patients.

Surgical intervention after vascular surgery usually occurs as a result of bleeding or thrombosis, whereas general surgical problems requiring operation after vascular surgery are unusual. The purpose of this study was to review the results of operations for general surgical problems done soon after major vascular surgery. From January 1985 to December 1989, 1,236 major vascular procedures were performed, and 15 patients developed significant postoperative general surgical problems including perforated duodenal ulcer (2), perforated diverticular disease (2), evisceration and dehiscence (2), liver infarct (1), gangrenous cholecystitis (2), clostridial myonecrosis (1), pseudomembranous colitis (1), and small bowel obstruction (4). The overall mortality was very high (47%), and the chance of dying was significantly higher (p less than 0.05) if the initial vascular procedure was an emergency (100% mortality). All the patients who died (n = 7) succumbed to sepsis. There was a long delay in diagnosis in all groups; however, the delay did not correlate with mortality. Although this is a study of a small group of patients with a very heterogenous group of complications, several observations can be made: (1) a general surgical problem after vascular surgery carries a very high mortality; (2) general surgical complications in postoperative vascular patients in whom the initial procedure was an emergency are very poorly tolerated and almost uniformly lethal; and (3) these elderly patients have multiple medical problems and seem unlikely to tolerate any septic insult.

Production of monoclonal antibodies to Naegleria fowleri, agent of primary amebic meningoencephalitis.

Monoclonal antibodies (MAbs) to Naegleria fowleri, the etiologic agent of primary amebic meningoencephalitis (PAM), have been produced and used as probes to identify N. fowleri amebae in brain sections of patients who died of that disease. These MAbs were characterized for their specificity by the indirect immunofluorescence assay (IIF), dot immunobinding assay (DIBA), and enzyme-linked immunotransfer blot technique (EITB). The MAbs reacted intensely with all strains of N. fowleri tested originating from different geographic areas in the IIF and DIBA tests, but showed no reactivity with four other species of Naegleria, N. gruberi, N. jadini, N. lovaniensis, and N. australiensis, or a strain of Acanthamoeba castellanii. In the EITB assay the MAbs reacted with the antigens of N. fowleri and produced intensely staining bands at the 160-, 104-, 93-, and 66-kilodalton (kDa) regions and several minor bands at the 30- and 50-kDa regions. The MAbs also reacted with the antigens of N. lovaniensis and produced a darkly staining band at 160 kDa and a diffusely staining band at 116 kDa, indicating that these antigens were shared by the two species. The MAbs, however, showed no reactivity with N. jadini and N. gruberi in the EITB assay.