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N Botros

Publications and source records attributed to N Botros.

8 recordsLinked to original sources
PubMed1995

A simulation algorithm for ultrasound liver backscattered signals.

In this study, we present a simulation algorithm for the backscattered ultrasound signal from liver tissue. The algorithm simulates backscattered signals from normal liver and three different liver abnormalities. The performance of the algorithm has been tested by statistically comparing the simulated signals with corresponding signals obtained from a previous in vivo study. To verify that the simulated signals can be classified correctly we have applied a classification technique based on an artificial neural network. The acoustic features extracted from the spectrum over a 2.5 MHz bandwidth are the attenuation coefficient and the change of speed of sound with frequency (dispersion). Our results show that the algorithm performs satisfactorily. Further testing of the algorithm is conducted by the use of a data acquisition and analysis system designed by the authors, where several simulated signals are stored in memory chips and classified according to their abnormalities.

Acoustics↗
PubMed1994

In vivo liver differentiation by ultrasound using an artificial neural network.

A pattern recognition algorithm and instrumentation for in vivo ultrasound human liver differentiation are presented. An available 16-MHz microprocessor-based data acquisition and analysis system with 6-bit resolution is used to capture, digitize, and store the backscattered ultrasound signal. The algorithm is based on a multilayer perception neural network using the backpropagation training procedure. The network is implemented to differentiate between normal and abnormal liver. Data earlier obtained from 18 volunteers with normal liver history and from 12 volunteers with liver abnormalities are used to test the algorithm. The power spectra of the backscattered signal from depths of 5, 6.5, and 8 cm in the liver are calculated. The acoustic attenuation coefficient is calculated by the log spectral difference technique over the frequency range from 1.5 to 4.5 MHz. The change of speed of sound with frequency (dispersion) is estimated over the 3-MHz bandwidth. The attenuation and velocity dispersion are used as differentiation features. The results show that of the 22 tested cases, the system differentiated correctly 19 and 20 cases when using the attenuation and the velocity dispersion, respectively. The average magnitude of dispersion of liver is estimated to be 1.67 +/- 0.1 m/s/MHz and about 2.3 +/- 0.18 m/s/MHz in the normal and abnormal cases, respectively. The overall performance of the system for liver differentiation is 91% for normal cases, and 86% for abnormal cases. The data files are also differentiated using the nearest neighbor statistical classifier. The results show that of the 30 tested cases, 23 files are differentiated correctly using the attenuation coefficient.

Humans↗
PubMed1994

Predominantly gastrointestinal symptoms and signs in 11 consecutive AIDS patients with gastrointestinal lymphoma: a multicenter, multiyear study including 763 HIV-seropositive patients.

OBJECTIVES: Gastrointestinal lymphoma is a distinct subgroup of lymphoma in HIV-seronegative patients. This study analyzes whether gastrointestinal lymphoma similarly forms a distinct clinical subgroup in HIV-seropositive patients. METHODS: Case control study of medical records of 763 human immunodeficiency virus-seropositive patients admitted to three university hospitals from 1986 through 1992, including 22 with non-Hodgkin's lymphoma. Eleven patients (50%) had gastrointestinal lymphoma, and 11 controls had extraintestinal lymphoma. RESULTS: The clinical presentation in patients with gastrointestinal lymphoma was dominated by gastrointestinal symptoms and signs and gastrointestinal complications. Common symptoms and signs included: change in bowel habits, gross or occult blood per rectum, involuntary weight loss, abdominal pain, abdominal tenderness, peripheral lymphadenopathy, cachexia, and hepatosplenomegaly. Significant gastrointestinal complications during the presenting admission included gastrointestinal bleeding in five, intestinal obstruction in one, and dysphagia from an esophageal stricture in one. Subsequent complications included a walled-off perforating gastric ulcer in one and obstructive jaundice in one. In contrast, the control patients with extraintestinal lymphoma had significantly fewer gastrointestinal symptoms and gastrointestinal complications (p < 0.001 and p < 0.01, respectively, Fisher's exact test). Upper gastrointestinal series or barium enema identified lymphomatous gastrointestinal lesions in all seven patients undergoing these tests. The pathologic diagnosis was made from endoscopic biopsies in six of six patients undergoing panendoscopy, and two of three patients undergoing lower endoscopy. Tumor sites included stomach in six, colon in three, ileum in two, esophagus in two, and duodenum in one. Eight patients had extraintestinal lesions at diagnosis, including four with extraabdominal extranodal lesions. The outcome of gastrointestinal lymphoma was poor with all therapies (mean combined survival = 3.6 +/- 2.2 months), and was not significantly different from that for the controls (mean survival = 4.1 +/- 2.7 months, Student's t test). CONCLUSIONS: This study suggests that gastrointestinal lymphoma in AIDS shares the poor prognosis and aggressive features of extraintestinal lymphoma in AIDS, but has unique localizing features at presentation of predominantly gastrointestinal symptoms and signs, and frequent gastrointestinal complications.

Adult↗
PubMedDate not supplied

An antigen reacting with das-1 monoclonal antibody is ontogenically regulated in diverse organs including liver and indicates sharing of developmental mechanisms among cell lineages.

The monoclonal antibody designated mAb Das-1, which was generated against a colon epithelial protein, reacts with the normal biliary epithelium and keratinocytes, which are among targets of tissue injury in ulcerative colitis. Moreover, mAb Das-1 reacts with abnormal cells in Barrett's esophagus and chronic cystitis profunda, as well as so-called 'oval cells' in the adult liver, which are considered oncogenic progenitor cells. To establish ontogenic regulation of mAb Das-1 reactivity, we studied 7- to 24-week-old human fetuses by immunohistochemistry. In liver, mAb Das-1 reactivity was further correlated with glycogen, dipeptidyl peptidase IV, glucose-6-phosphatase and gamma-glutamyl transpeptidase expression. mAb Das-1 reacted with cells in organs arising from the pharyngeal cleft (thymus), primitive gut (oral cavity, pharynx, lung, esophagus, stomach, biliary tree, pancreas, liver, colon), ureteric bud (renal tubules, collecting duct), mesonephros (kidney, testis), mesoderm (muscle) and elsewhere (skin, adrenal cortex). In distinction from the adult liver, mAb Das-1 staining was more pronounced in hepatoblasts compared with biliary cells. In adult tissues, however, mAb Das-1 reactivity was restricted to the colon, biliary epithelium, keratinocytes, and ciliary body. These data indicated that the mAb Das-1 recognized epitopes in fetal cells of diverse ectodermal, mesodermal and endodermal origin, compatible with sharing of lineage mechanisms in tissues. Reactivation of mAb Das-1 staining in epithelial precancerous conditions, including carcinomas arising in these organs, is compatible with oncofetal regulation of the antigen, which will facilitate analysis of cell subpopulations during organ development, regeneration and oncogenesis.

Adult↗