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Biomedical subjects

R C Sanders

Publications and source records attributed to R C Sanders.

At least 73 records · Page 4Linked to original sources

The diagnostic gap in diarrhoeal aetiology.

It is well established that rotaviruses of group A are the most important cause of severe diarrhoea in children. The causes of most cases of infectious diarrhoea still remain unidentified, however, and there must be other viruses to be found. 'Novel' rotaviruses have recently been discovered, mainly in animals (serogroups B and C in pigs and humans, D in birds, and one or more further groups in sheep and other mammals). Except for the group B virus which has caused widespread outbreaks of quite severe diarrhoea in adults in China (still not reported from outside China) these novel rotaviruses are rarities in the human and probably represent uncommon zoonotic infections. We speculate that the Chinese virus might have arisen by reassortment of genetic segments of animal group B viruses or perhaps by mutation, and so became infectious for man. The problem of identifying and determining the importance of small round viruses is reviewed. It seems likely that the group of small, round structured viruses, including Norwalk and the viruses of plainly calicivirus morphology, are all representatives of a whole group of enteric caliciviruses. Until they can be more easily cultivated it will be difficult to make diagnostic reagents available to all. Astroviruses and genuine parvoviruses have been found by many people in many countries. Astroviruses are probably more important as pathogens in lambs than in children or calves; parvoviruses can only be established as significant in epidemics. The coronavirus-like particles, first found in Vellore and Bristol, are still enigmatic and their role in diarrhoea is uncertain. Toroviridae, recently discovered as causes of diarrhoea in ungulates, do not seem to be at all important as causes of diarrhoea in humans. Possibly fruitful approaches to future searches are outlined: firstly to make more extensive use of immuno-electron microscopy; and secondly to try to improve existing tissue culture systems to make them more sensitive to enteric viruses.

Animals↗

Update on prostatic ultrasound.

Although there is good evidence that carcinomas of the prostate are usually seen as echopenic masses within the external zone of the prostate, it is unclear how often an echopenic mass has an origin other than carcinoma of the prostate. Technical problems at the periphery of the gland not uncommonly create echopenic areas on an artifactual basis. Whether ultrasound will prove to be a satisfactory screening method for the detection of carcinoma of the prostate is yet to be decided. Prospective studies are in progress, but it has not yet been established whether prostate screening is a worthwhile procedure. The best possible equipment is required to detect these subtle lesions; cheap equipment will probably not give adequate results.

Aged↗

Theophylline-induced upregulation of A1-adenosine receptors associated with reduced sensitivity to convulsants.

Chronic administration of theophylline (50 mg/kg twice daily for 14 consecutive days) significantly increased the specific binding of [3H]CHA in membranes of the cerebral cortex and cerebellum of the rat, but not in membranes derived from the hippocampus or diencephalon. To characterize further the upregulation of A1 = adenosine receptors induced by theophylline, saturation analysis with [3H]CHA was performed in membranes of the cerebral cortex and cerebellum. In both saline- and theophylline-treated cortical membranes the binding isotherms for [3H]CHA could be resolved into receptor affinity states having respectively high (KH) and low (KL) affinity for [3H]CHA. The high and low affinity dissociation constants obtained from theophylline-exposed membranes of the cerebral cortex were 1.14 nM and 25.2 nM and did not differ significantly from the corresponding values in saline-treated animals. Chronic exposure to theophylline did, however, produce significant increases in the densities of both the high and low affinity forms of A1-adenosine receptors in the cerebral cortex. Qualitatively and quantitatively similar results were observed in cerebellar membranes. These results suggest that chronic exposure to theophylline increases the density of A1-receptor in the cerebral cortex and cerebellum with no concomitant changes in the ability of [3H]CHA to distinguish separate agonist affinity states of the receptor. The physiological significance of theophylline-induced upregulation was assessed by determining seizure thresholds for convulsants in rats treated chronically with saline or theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

Epidemiology of rotavirus in a periurban Gambian community.

Short, well demarcated epidemics of rotavirus diarrhoea were observed during two consecutive cool, dry seasons in The Gambia. This seasonal pattern has now been documented for 4 consecutive years. During the 1985/86 epidemic, transmission was intense, with a clinical attack rate for infants of 36%. During this outbreak it was estimated that asymptomatic virus-shedding was two-thirds as common as symptomatic infection. Rotavirus diarrhoea was more severe than diarrhoea due to all other causes and clinical rotavirus infection was associated with weight loss in the post-infection period. Non-epidemic periods were characterized by very occasional mild cases and asymptomatic virus-shedding in neonates. There was a change in RNA electropherotypes from a predominantly long pattern in 1983/84 and 1984/85 to short patterns in 1985/86.

Child, Preschool↗

The multiloculated renal mass: considerations and differential features.

1. Many diverse disease processes may result in a multiloculated renal mass. 2. The term "multilocular cyst" is purely descriptive and should not be used as a specific diagnosis. 3. The management of this diverse group of diseases is controversial. There is insufficient information concerning the accuracy of percutaneous biopsy to permit one to base management decisions on such a biopsy in most of these masses. The cystic diseases (septated cyst, localized cystic disease, segmental multicystic kidney) should be managed conservatively. Most cases of arteriovenous communication are readily diagnosed angiographically and managed by vascular occlusive techniques or by surgery. The remaining multiloculated renal masses usually require surgical removal for histologic diagnosis or definitive therapy or both.

Carcinoma, Renal Cell↗

Cystic hygromas in children: sonographic-pathologic correlation.

The sonographic findings in eight children with surgically proved cystic hygroma were reviewed and correlated with the pathologic specimens. Six tumors occurred in the neck, one occurred in the axilla, and one involved the soft tissues of the thigh, scrotum, and pelvis. A cystic hygroma characteristically appears as a multiloculated cystic mass with septa of variable thickness that contain solid components arising from the cyst wall or the septa. Correlation of the sonogram with the pathologic specimen demonstrated that the echogenic component corresponded to a cluster of abnormal lymphatic channels, too small to be resolved with ultrasound. Large lesions had ill-defined boundaries, with cystic components dissecting between normal tissue planes. Sonographically, one can usually differentiate these tumors from other cervical masses, especially soft-tissue hemangiomas. Sonography is also helpful in determining the extent of the lesion before surgery and in assessing postoperative complications and recurrences.

Axilla↗

Sonographic findings in adenomyosis of the uterus.

In an attempt to define better the sonographic findings of adenomyosis of the uterus, we reviewed sonograms in seven cases of pathologically proven extensive adenomyosis without associated uterine diseases. In all cases, the uterus was enlarged. In five cases, the posterior wall of the uterus was thickened, and echoes in the endometrial cavity were eccentric. Six cases showed a slight decrease in uterine echogenicity. One case had sonographic findings suggestive of a calcified leiomyoma. The diagnosis of adenomyosis cannot be made conclusively by sonography. However, it can be suggested if the uterus is slightly enlarged and if the posterior portion of the myometrium is anechoic and thickened.

Endometriosis↗

Primary adrenocortical carcinoma: sonographic evaluation with clinical and pathologic correlation in 26 patients.

The sonograms of 26 patients (19 adults and seven children) with pathologically proven diagnoses of primary adrenocortical carcinoma were evaluated. Clinical corroboration was obtained in all cases. The size of the lesions ranged from 3 to 22 cm. The five smaller lesions (3-6 cm) showed a homogeneous echo pattern, similar to renal cortical echogenicity. The 21 larger lesions varied in echo texture, having a heterogeneous appearance with focal or scattered echopenic or echogenic zones representing areas of tumor necrosis, hemorrhage, and/or, rarely (19%), calcification. Even the largest lesions were fairly well delineated, often with a lobulated border. Few (7/26 or 27%) showed a surrounding echogenic thin capsulelike rim. All five small lesions showed clinical evidence of endocrine activity. Larger lesions were hormonally active less often (9/21 or 43%). Twelve patients (46%) showed no sign of endocrine activity and presented with symptoms such as fever, weight loss, abdominal discomfort, abdominal mass, hematuria, and hypertension. In the pediatric and adolescent age group (0-16 years), all tumors were hormonally active, while only seven (37%) of tumors in the adult population (17-69 years) were hormonally active. Unfortunately no echo pattern was characteristic enough to allow differentiation of adrenal adenoma from carcinoma. Smaller lesions are more likely to be benign, and larger lesions with areas of necrosis, hemorrhage, and calcification are more likely to be malignant.

Adolescent↗

Multicystic dysplasia and crossed renal ectopia.

Multicystic renal dysplasia in a crossed fused or nonfused ectopic kidney is a rare occurrence that produces unusual imaging findings. In four such cases in neonates, three presented with a palpable abdominal mass and one was discovered in utero with maternal sonography. In three cases, sonography showed a multicystic mass, contiguous with the lower pole of the orthotopic kidney. In the fourth infant, a crossed, tiny dysplastic kidney was not visualized, but its markedly dilated ectopic ureter was seen traversing the spine on CT. Ureteropelvic junction obstruction was present in the three fused orthotopic kidneys. The characteristic imaging findings of multicystic dysplasia and crossed renal ectopia include a multicystic mass of variable size that is contiguous with the lower pole of a hydronephrotic, malrotated kidney; ureteral displacement and/or dilatation; and contralateral absence of the kidney and its renal artery.

Abnormalities, Multiple↗

Cysts in pregnancy discovered by sonography.

The incidence of cysts in pregnancy was established with ultrasound. In 3,330 pregnant patients who underwent sonography, 38 adnexal cystic lesions (1.14%) were found. All but two cysts were discovered before 16 weeks. Follow-up showed that the majority of the cystic lesions resolved spontaneously; these were presumed to represent corpus luteum cysts. Five patients underwent surgery because of persistent cystic lesions; a mucinous cystadenoma, a benign cystic teratoma, a paraovarian cyst, an inclusion cyst, and a tuboovarian abscess were found. Septations and echogenic material were seen within the cystic teratoma and the tuboovarian abscess but the sonographic features of the other operated lesions were identical to those seen in the corpus luteum cysts.

Abscess↗

Routine detection of human rotavirus by latex agglutination: comparison with enzyme-linked immunosorbent assay, electron microscopy and polyacrylamide gel electrophoresis.

A commercially available latex agglutination test, RotaScreen (Mercia Diagnostics Ltd., West Byfleet, Surrey, U.K.) was evaluated for the detection of human rotaviruses in stool specimens. The results obtained were compared with those from 3 other routine assay systems used in this laboratory: enzyme-linked immunosorbent assay (ELISA), electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) of viral ribonucleic acid. 400 stool samples were examined by the 4 assay systems under routine conditions. RotaScreen latex agglutination was found to be more sensitive than EM and PAGE, and highly specific for rotavirus antigens.

Adult↗

Prostatic evaluation by transrectal sonography with histopathologic correlation: the echopenic appearance of early carcinoma.

Fifty-two patients with clinical stage A and B carcinomas of the prostate were imaged by ultrasound (US) transrectally with a 5-MHz linear array transducer and transabdominally with a 3-MHz sector scanner prior to radical prostatectomy. The fresh specimens of 44 prostate glands were scanned in a water bath with a 5-MHz linear array transducer in multiple planes. In all cases, histopathologic correlation was obtained. Prostatic carcinoma presented as an echopenic lesion in 54% of the specimens, as a slightly hypoechoic area in 22%, and could not be identified in 24% because of its isoechoic characteristics. In contrast to many previous reports, no instance of echogenic cancer was observed.

Adenocarcinoma↗

Ectopic ureter and ureterocele: their varied sonographic manifestations.

The sonographic examinations of four patients with simple ectopic ureters and 11 with ectopic ureteroceles were reviewed to determine distinguishing characteristics. Ectopic ureters, in cases of extreme dilatation and tortuosity, sometimes mimic multiseptated, cystic abdominal masses. However, the proximal portions of some severely dilated ureters are surprisingly small. Ectopic ureters sometimes indent the lower vesical wall, simulating a ureterocele. Ectopic ureteroceles are dynamic structures, changing in shape and size according to intravesical pressure. The lower pole of a duplex kidney may be difficult to detect because of displacement by the dilated upper renal pelvis and ureter. The renal parenchyma associated with an ectopic ureter may be equally difficult or impossible to find because of diminutive dysplasia or, less commonly, acquired atrophy. Dysplasia is characterized sonographically by highly echogenic parenchyma, lack of corticomedullary differentiation, and occasionally massive enlargement by cysts. Ectopic ureters and ureteroceles can be identified by fetal sonography.

Adolescent↗

The echogenic focus in prostatic sonograms, with xeroradiographic and histopathologic correlation.

The sonograms of 42 patients scanned before and after radical prostatectomy were reviewed, giving specific attention to echogenic foci. All patients had clinical stage A or B adenocarcinoma of the prostate. Comparison of the scans with xeroradiographic and histopathologic studies showed all echogenic foci, with or without acoustic shadowing, to represent prostatic calcifications. Calcifications were located in the central portion of the gland exclusively, either immediately adjacent to the urethra or at the margins of the "internal gland", separate from the peripheral location of small tumors. With carcinomatous spread toward the urethra, calculi were found surrounded by tumor. This was considered a result of secondary involvement rather than dystrophic tumor calcification. Prostatic calcifications seem unrelated to the development of adenocarcinoma but must be recognized to prevent erroneous interpretation.

Calcinosis↗

Neonatal uterine morphology as seen on real-time US.

The uterus in the neonate is prominent and readily identified on ultrasonography (US). The neonatal uterus is larger than the prepubertal uterus as a result of residual stimulation from maternal hormones. The uterus was visualized in 31 of 35 (89%) infant girls examined with real-time US. Mean uterine length was 3.4 cm. The majority of the uteri were tubular or spade-shaped, with the anteroposterior diameter of the cervix equal to or greater than the anteroposterior diameter of the fundus. The endometrial cavity was visualized in 30 (97%), a myometrial halo in nine (29%), and a small amount of endometrial fluid in seven (23%) of the uteri.

Cervix Uteri↗