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Biomedical subjects

A Aslani

Publications and source records attributed to A Aslani.

14 recordsLinked to original sources
PubMed2003

[A rare case of cannabis arteritis].

A 24-year old woman, heavy cannabis smoker with progressive Raynauld's phenomenon and digital necrosis is presented. Systemic sclerosis and other connective tissue disorders as well as arteriosclerosis and arterial emboli were excluded with appropriate laboratory examinations. Arteriography revealed multiple forearm, palmar and digital occlusions with corkscrew-shaped vessels. Based on these characteristic arteriography and clinical findings, the diagnosis of cannabis-arteritis was finally retained. With careful necrectomy, conservative wound dressings and secondary prostacyclin therapy a complete healing of digital necrosis was observed. There was no recurrence during the 6 month-follow-up. This observation demonstrates that cannabis may represent a possible cofactor in the pathogenesis of arteritis in young smokers. Early recognition is important to avoid irreversible complications such as loss of digits.

Adult↗
PubMed2002

Extensor-tendon hypoplasia and multiple pterygia: Escobar syndrome in a 7-year-old boy.

Escobar syndrome is a rare condition with autosomal-recessive inheritance, characterised by multiple pterygia, kyphoscoliosis, multiple joint contractures and craniofacial dysmorphisms. A number of other abnormalities are also attributed to the syndrome. Here, we present a case of isolated extrinsic extensor-tendon hypoplasia of the right index finger in a 7-year-old patient with Escobar syndrome. To our knowledge, this has not been previously described in connection with this syndrome.

Abnormalities, Multiple↗
PubMed2001

Complementary intrastrand base pairing during initiation of Herpes simplex virus type 1 DNA replication.

The herpes simplex virus type 1 origin of DNA replication, oriS, contains three copies of the recognition sequence for the viral initiator protein, origin binding protein (OBP), arranged in two palindromes. The central box I forms a short palindrome with box III and a long palindrome with box II. Single-stranded oriS adopts a conformation, oriS*, that is tightly bound by OBP. Here we demonstrate that OBP binds to a box III-box I hairpin with a 3' single-stranded tail in oriS*. Mutations designed to destabilize the hairpin abolish the binding of OBP to oriS*. The same mutations also inhibit DNA replication. Second site complementary mutations restore binding of OBP to oriS* as well as the ability of mutated oriS to support DNA replication. OriS* is also an efficient activator of the hydrolysis of ATP by OBP. Sequence analyses show that a box III-box I palindrome is an evolutionarily conserved feature of origins of DNA replication from human, equine, bovine, and gallid alpha herpes viruses. We propose that oriS facilitates initiation of DNA synthesis in two steps and that OBP exhibits exquisite specificity for the different conformations oriS adopts at these stages. Our model suggests that distance-dependent cooperative binding of OBP to boxes I and II in duplex DNA is succeeded by specific recognition of a box III-box I hairpin in partially unwound DNA.

Adenosine Triphosphate↗
PubMed2000

A novel conformation of the herpes simplex virus origin of DNA replication recognized by the origin binding protein.

The Herpes simplex virus type I origin binding protein (OBP) is a sequence-specific DNA-binding protein and a dimeric DNA helicase encoded by the UL9 gene. It is required for the activation of the viral origin of DNA replication oriS. Here we demonstrate that the linear double-stranded form of oriS can be converted by heat treatment to a stable novel conformation referred to as oriS*. Studies using S1 nuclease suggest that oriS* consists of a central hairpin with an AT-rich sequence in the loop. Single-stranded oligonucleotides corresponding to the upper strand of oriS can adopt the same structure. OBP forms a stable complex with oriS*. We have identified structural features of oriS* recognized by OBP. The central oriS palindrome as well as sequences at the 5' side of the oriS palindrome were required for complex formation. Importantly, we found that mutations that have been shown to reduce oriS-dependent DNA replication also reduce the formation of the OBP-oriS* complex. We suggest that oriS* serves as an intermediate in the initiation of DNA replication providing the initiator protein with structural information for a selective and efficient assembly of the viral replication machinery.

Base Sequence↗
PubMed2000

The predictive value of body protein for chemotherapy-induced toxicity.

BACKGROUND: The use of body surface area in determining chemotherapy dosing, particularly in the obese, remains controversial. Total body nitrogen (TBN) measurement in patients with serious illness has been suggested to be an accurate predictor of clinical course. The ability of TBN to predict chemotherapy-induced neutropenia was examined in the current study. METHODS: TBN measurements were performed in 31 female outpatients with breast carcinoma who were undergoing standard cyclophosphamide, methotrexate, and 5-fluorouracil (CMF)-based chemotherapy (median age, 48 years; range, 26- 77 years). TBN was measured using the in vivo neutron capture analysis technique on Day 1 of Cycles 2-6. The chemotherapy toxicity index used was the absolute neutrophil count nadir (ANCN). Neutropenia was defined as an ANCN < 1.0 x 10(9)/L. The nitrogen index (NI) (TBN expressed as a percentage of age-, gender-. and height-matched healthy patients) then was compared with the corresponding ANCN values. RESULTS: Using receiver operating characteristics analysis, a "cut-off" value of NI = 0.89 was found. In this group of patients, when the NI was < 0.89, 11 of 13 courses in 7 patients (85%) led to an ANCN of < 1.0 x 10(9)/L, and when the NI was > 0.89, 29 of 109 courses (27%) led to an ANCN of < 1.0 x 10(9)/L (P < 0.0001). CONCLUSIONS: In this small group of breast carcinoma patients, the NI was found to be the most powerful predictor of neutropenia after CMF-based chemotherapy. The authors conclude that NI may be a useful clinical tool in identifying patients at a higher risk of chemotherapy-induced toxicity when widely distributed drug combinations such as CMF are used, and warrants further study with other commonly used drugs or drug regimens.

Adenocarcinoma↗
PubMed2000

Body surface area: Du Bois and Du Bois revisited.

The Du Bois and Du Bois body surface area (BSA) equation is used widely to normalise physiological parameters. However, that only nine subjects were used in its derivation does not appear to be well known and does not justify its ubiquitous application. Furthermore, the derivation appears to be hampered by a lack of modern statistical methods and the omission of a large amount of available data. We have shown that the omitted data, obtained by measurement of the length of body parts, were identical to the data obtained by encasing subjects in moulds ¿BSA (moulds; cm2) = [1.00 (0.02)] x BSA (linear measurements) + [123 (347)]¿. Non-linear regression analysis of the BSA of all 42 subjects reported by Du Bois and Du Bois gave new values for the constants of the model ¿BSA (cm2) = 94.9 x [weight (kg)0.441] x [height (cm)0.655]¿. Although the original equation obtained by Du Bois and Du Bois was found to be adequate in adults, we recommend that it should not be used in daily practice, owing to the low number of subjects used in its derivation. The work presented here has placed the original results of Du Bois and Du Bois on a more robust statistical footing, yielding values for the model constants that would have been obtained if Du Bois and Du Bois had had access to modern statistical methods.

Adult↗
PubMed2000

Comparing different methods of assessing body composition in end-stage renal failure.

BACKGROUND: Accurate measurement of nutritional status in patients with end-stage renal disease is important because of its clear association with prognosis. Total body water (TBW) has additionally been recently recognized as an independent prognostic value because of its relationship with hypertension and cardiac morbidity. The current study was designed to assess the utility of surrogate markers of nutritional state and TBW in patients with end-stage renal disease. METHODS: Fifty-four patients with renal disease were studied. TBW obtained using the deuterium dilution technique was compared with estimates derived from anthropometric measures of TBW, including 58% body weight, Watson equations, and bioelectrical impedance analysis (BIA). Anthropometrically derived fat-free mass (FFM) was compared with BIA-derived estimates. Total body nitrogen (TBN) measurements were correlated with TBW estimates and BIA-derived resistance. RESULTS: TBW was significantly underestimated by the Watson equation (mean difference, -1.751 L, P = 0.01) and the 58% body weight approximation significantly overestimated it (mean difference, 1.792 L, P = 0.04). The Kushner BIA estimation of TBW did not significantly differ from that of the gold standard determined from D2O dilution (mean difference, -1.221 L, P = 0.12) and was also the method that showed the best agreement with the D2O estimate. However, the limits of agreement were large. Accurate prediction equations for FFM (FFM = -21.768 + 0.001 x ht2 + 6630.669 x 1/R + 0.312 x wt, R2 = 0.95) and TBN (TBN = -668.324 - 3.963 x age + 10.133 x wt + 0. 045 x ht2 + 32141.457 x 1/R, R2 = 0.91) were derived from BIA obtained resistance. CONCLUSIONS: The estimation of TBW varies significantly depending on the method of calculation. BIA is the most accurate surrogate marker for the measurement of both TBW and other parameters of body composition.

Adipose Tissue↗
PubMed2000

Plasma sample preparation by ultrafiltration for FTIR analysis.

Total body water (TBW) may be significantly altered with disease. Isotope dilution techniques, considered to be the "gold standard" methods for measuring TBW, are expensive, time consuming and require considerable expertise, especially during the sample preparatory phase. In this study, a new method, ultrafiltration (UF), was hypothesised to be an efficient alternative to vacuum sublimation (VS) in the preparation of plasma samples for Fourier Transform Infra Red (FTIR) determination of TBW. Deuterium Oxide (D2O) concentrations were prepared in human plasma and subjected to both techniques. FTIR analysis was carried out on the resulting VS and UF solutions and on D2O concentrations in distilled water. The resulting absorbance values were then statistically compared. Urea concentrations prepared in D2O-containing plasma were also compared to "blank" plasma to investigate the effect of high plasma urea concentration on the resulting H2O/D2O mixture obtained during UF Paired t-tests showed that the VS plasma samples (p=0.003), but not the UF samples (p=0.9), were significantly different to D2O standards prepared in distilled water. While there was no evidence of an effect of urea on UF at low (0.4 g/L) D2O concentration, a marginal (p=0.04) effect occurred at a higher (1.6 g/L) D2O level. Throughput of samples was much more efficient with the UF technique. These findings indicate that the new UF method is an accurate, more efficient method of plasma sample preparation than the VS method in the FTIR determination of TBW.

Blood Chemical Analysis↗
PubMed1999

Changes in body composition during breast cancer chemotherapy with the CMF-regimen.

Weight gain is a reported problem associated with adjuvant chemotherapy for breast cancer and often generates psychosocial stress in women [1]. It also may affect prognosis and survival. Changes in body composition and weight during chemotherapy, particularly adjuvant treatment of breast carcinoma, have been previously reported [1-3]. Multiple reasons for this weight gain have been suggested though few theories have been scientifically validated [4]. The aim of this study was to investigate body composition and its relationship to weight change associated with the CMF-based breast cancer chemotherapy protocols. Total body nitrogen (TBN), body fat, total body water (TBW), and anthropometric measurements were conducted on 25 female out-patients (median age 47, range 26-70 years) receiving adjuvant CMF-based chemotherapy for breast cancer. Total body nitrogen was measured using the In Vivo Neutron Capture Analysis (IVNCA) technique (on day 1 of cycles 2-6) and TBP was calculated by multiplying TBN by 6.25 [5]. Nitrogen Index (NI) was calculated by expressing TBN as a percentage of normal. There was a significant increase in mean body weight during chemotherapy of 2.35 kg (p < 0.0001). Serial measurements showed no significant change in mean TBN, NI, or percentage body fat. Break down of body weight showed a significant increase in mean TBW of 0.79 kg (p = 0.003) and mean fat mass of 1.49 kg (p = 0.008). We conclude that weight gain observed during adjuvant chemotherapy for breast carcinoma is primarily due to an increase in fat and TBW.

Adult↗
PubMed1999

Determination of skeletal muscle and fat-free mass by nuclear and dual-energy x-ray absorptiometry methods in men and women aged 51-84 y (1-3).

BACKGROUND: Skeletal muscle mass (SMM) and fat-free mass (FFM) are important variables in nutritional studies. Accurate techniques for measuring these variables have not been thoroughly validated in elderly subjects. OBJECTIVES: The objectives of this study were to 1) compare SMM values derived from dual-energy X-ray absorptiometry (DXA) with those calculated by a nuclear method from total body potassium (TBK) and total body nitrogen (TBN) measurement (both: KN) in older subjects, and 2) assess the accuracy of FFM measurement by DXA in these subjects. DESIGN: TBK, TBN, DXA (model XR36; Norland, Fort Atkinson, WI), bioimpedance, and anthropometric measurements were performed on healthy women (n = 50) and men (n = 25) aged 51-84 y. RESULTS: Mean SMM by KN was not significantly different from SMM by DXA in either sex. SMM by KN predicted SMM by DXA with an SEE of 2.1 kg (r = 0.95, P < 0.0001 for women and men together). In the men, FFM by DXA agreed well with FFM estimated by TBK, skinfold thicknesses, bioimpedance analysis, and a multicompartment model. In women, FFM by DXA was 4-5 kg less than that by the other methods (P < 0.01). Truncal fat was related to intermethod FFM differences (r = 0.58, P < 0.0001). CONCLUSIONS: These data indicate that 1) either the nuclear or the DXA method can be applied to estimate SMM in healthy older subjects, and 2) the Norland DXA instrument significantly underestimates FFM in older women, in part, because of the influence of truncal adiposity.

Absorptiometry, Photon↗