Electrode Positioning for Reliable Telemetry ECG Recordings During Social Stress in Unrestrained Rats

We describe a surgical procedure for optimizing the location of telemetry ECG leads in rats. The new location was aimed at obtaining an accurate representation of ECG features throughout the cardiac cycle by limiting the voltage instability usually observed during intense somatomotor activity and improving the signal-to-noise ratio. The two electrodes (wire loops) were fixed on the dorsal surface of the xiphoid process and in the anterior mediastinum close to the right atrium. The implantation procedure was fast, little invasive, and allowed animals to completely recover from intervention. The performance of the “improved” location (IL, n = 10) with respect to two subcutaneous (SC) positionings (“conventional positioning,” CSP, n = 5; “updated location,” USL, n = 5) was evaluated by comparing ECGs obtained in baseline, stress and recovery conditions and during different behavioral activities (immobility and grooming). The resident-intruder test (emotional/physical challenge) was chosen as experimental stress paradigm. The noise level of ECGs obtained from IL rats was lower than in CSP and USL animals, in all recording conditions. Percentages of correctly recognized beats (CRBs) over the total number of beats (TBs) were significantly higher in IL rats than in CSP and USL animals, both in baseline conditions (99% vs. 11% and 40%) and situations involving high somatomotor activity (stress: 97%, 5% and 16%; recovery: 97%, 7%, and 15%) (p < 0.01). The performance of IL as compared to CSP and USL was also better when percentages during grooming and immobility were considered (grooming: 93% vs. 4% and 23%; immobility: 97%, 6%, and 33%; p < 0.01).     

Duplex-Doppler assessment of cirrhosis in patients with chronic compensated liver disease

Portal venous flow velocity (PFV) was measured with duplex-Doppler equipment in 50 normal subjects and in 117 patients with suspected chronic liver disease who showed no evidence of decompensation such as ascites, hepatic encephalopathy, jaundice or oesophageal bleeding. All the patients underwent percutaneous liver biopsy which demonstrated non-cirrhotic liver disease in 58 cases (CH-patients: steatosis 8, persistent chronic hepatitis 8, active chronic hepatitis 42) and liver cirrhosis in the other 59 cases (LC-patients). The normal subjects and the CH-patients had similar values of max-PFV and mean-PFV (max-PFV 26.7±3.2 and 25.7±3.4 cm/s respectively; mean-PFV 22.9±2.8 and 22.4±3.8 cm/s respectively). The LC-patients’ values (max-PFV 19.3±3.5; mean-PFV 16.9±2.9) were significantly lower than those of the normal subjects (P<0.001) and of the CH-patients (P<0.001). Considering the normal max-PFV to be in the range 20–33.1 cm/s (mean±2 s.d. of the normal subjects, 95% confidence limits), max-PFV was reduced in 0/50 normal subjects, 1/58 CH-patients and 39/59 LC-patients (66.1% sensitivity; 98.2% specificity). In conclusion, the duplex-Doppler measurement of PFV is of great interest in the diagnostic study of patients with suspected chronic compensated liver disease and in the early diagnosis of cirrhosis. A low max-PFV is a reliable pointer to liver cirrhosis, whereas a normal max-PFV indicates a non-cirrhotic liver disease but is less probative. Each centre should standardize normal PFV values in order to establish their own threshold value for diagnosing liver cirrhosis.     

Crystallographic characterization of geometry and conformation of TOAC,a nitroxide spin-labelled Cα,α-disubstituted glycine,in simple derivatives and model peptides *

The molecular and crystal structures of one derivative and two oligopeptides of TOAC, a nitroxide spin-labelled C^αα-disubstituted glycine, have been determined by X-ray diffraction. The derivative is the 5(4H)-oxazolone from Piv-TOAC-OH; the oligopeptides are Z-TOAC-(L-Ala)₂-NHtBu sesquihydrate and p BrBz-TOAC-(L-Ala)₂-TOAC-L-Ala-NHtBu hemihydrate. Incipient and fully developed right-handed 3₁₀-helical conformations are formed by both independent molecules in the asymmetric unit of the terminally blocked tripeptide amide and the terminally blocked pentapeptide amide, respectively. The average geometry and preferred conformation for the piperidine ring of the TOAC residues are also discussed in detail. © Munksgaard 1996.     

Characterization and Properties of an Inhibitor of Factor VIII in the Plasma of Patients with Hemophilia A Following Repeated Transfusions

A circulating anticoagulant, which specifically inhibits Factor VIII (AHF),has been detected in some patients with hemophilia A who had receivedmultiple transfusions. The inhibitor was quantitated by measurement of thedegree of inactivation of Factor VIII. The data presented provide strongevidence for the antibody nature of the Factor VIII inhibitor in hemophilia:(1) All specific inhibitory activity of serum was detected in the G globulinobtained by chromatography of the sera on DEAE cellulose. (2) Fab fragments obtained by digestion of the G globulin with papain, contained 18-22per cent of the specific inhibitory activity, while Fc fragments contained0.4-3 per cent. F(ab')₂ fragments obtained by digestion with pepsin contained 36-61 per cent of the specific inhibitory activity of G globulin. (3)The level of the inhibitor of Factor VIII increased sharply following transfusions of blood and decreased slowly to its preinfusion level. (4) When smallamounts of inhibitor were incubated in vitro with excess Factor VIII, theinhibitor activity was decreased. Infusion of Factor VIII into a patient with alow level of inhibitor decreased the inhibitor activity. (5) Clearance of theisologous inhibitor from the circulation of a normal subject was rapid.

Submitted on December 16, 1966 Accepted on February 9, 1967     

NAEVUS LIPOMATOSUS CUTANEUS SUPERFICIALIS (HOFFMAN-Z URHELLE)

Summary.— The first example of this rare disorder seen in Australia is presented. The clinical and histological pictures are distinctive, but the precise origin of the condition remains unknown. The various theories relating to aetiology are discussed.     

INTERLEUKIN 6 GENE-TRANSFECTED MOUSE MAMMARY ADENOCARCINOMA: TUMOUR CELL GROWTH AND METASTATIC POTENTIAL

Cells from the spontaneous metastatic TSA mammary adenocarcinoma of BALB/C mouse were transfected with the murine (interleukin-6) IL6 gene. The clone (TSA-IL6) secreting the largest amount of IL6 displayed an in vitro increased growth rate compared with that of TSA cells transfected with the neomycin resistance gene only (TSA-neo). TSA-IL6 cell colonies consisted mainly of fusiform cells and TSA-neo colonies of polygonal cells. When subcutaneously (s.c.) injected in syngeneic mice, TSA-IL6 cells gave rise to tumours that grew significantly slower than TSA-neo cell tumours. Microscopically, TSA-IL6 tumours displayed a fascicular pattern of growth, associated with a very scanty macrophage infiltrate. S.c. TSA-IL6 tumours were significantly less metastatic than TSA-neo tumours. By contrast, following intravenous (i.v.) challenge, TSA-IL6 cells produced 5–7 times more lung metastases than TSA-neo cells. The i.v. TSA-IL6 cell lung metastases showed a marked macrophage infiltrate and a rich vascularization. The high in vitro TSA-IL6 cell growth rate is attributable to the IL6-induced production of growth factors, some of which possess heparin-binding properties, such as amphiregulin. The differences in vascularization and macrophage infiltrate may underlie the observed differences between s.c. TSA-IL6 tumour growth with low spontaneous metastatic potential and the widespread growth of i.v. metastasis. © 1997 John Wiley & Sons, Ltd.