Prediction of Wound Failure in Patients with Head and Neck Cancer Treated with Free Flap Reconstruction: Utility of CT Perfusion and MR Perfusion in the Early Postoperative Period

BACKGROUND AND PURPOSE

Free flap reconstruction in patients with head and neck cancer carries a risk of postoperative complications, and radiologic predictive factors have been limited. The aim of this study was to assess the factors that predict free flap reconstruction failure using CT and MR perfusion.

MATERIALS AND METHODS

This single-center prospective study included 24 patients (mean age, 62.7 [SD, 9.0] years; 16 men) who had free flap reconstruction from January 2016 to May 2018. CT perfusion and dynamic contrast-enhanced MR imaging with conventional CT and MR imaging were performed between 2 and 4 days after the free flap surgery, and the wound assessments within 14 days after the surgery were conducted by the surgical team. The parameters of CT perfusion and dynamic contrast-enhanced MR imaging with conventional imaging findings and patient demographics were compared between the patients with successful free flap reconstruction and those with wound failure as appropriate. P < .05 was considered significant.

RESULTS

There were 19 patients with successful free flap reconstruction and no wound complications (mean age, 63.9 [SD, 9.5] years; 14 men), while 5 patients had wound failure (mean age, 58.0 [SD, 5.7] years; 2 men). Blood flow, blood volume, MTT, and time maximum intensity projection (P = .007, .007, .015, and .004, respectively) in CT perfusion, and fractional plasma volume, volume transfer constant, peak enhancement, and time to maximum enhancement (P = .006, .039, .004, and .04, respectively) in dynamic contrast-enhanced MR imaging were significantly different between the 2 groups.

CONCLUSIONS

CT perfusion and dynamic contrast-enhanced MR imaging are both promising imaging techniques to predict wound complications after head and neck free flap reconstruction.

Effect of Low-Dose Rapamycin on Senescence Markers and Physical Functioning in Older Adults with Coronary Artery Disease: Results of a Pilot Study

Rapamycin, an mTOR inhibitor affects senescence through suppression of senescence-associated secretory phenotype (SASP). We studied the safety and feasibility of low-dose rapamycin and its effect on SASP and frailty in elderly undergoing cardiac rehabilitation (CR). 13 patients; 6 (0.5mg), 6 (1.0mg), and 1 patient received 2mg oral rapamycin (serum rapamycin <6ng/ml) daily for 12 weeks. Median age was 73.9±7.5 years and 12 were men. Serum interleukin-6 decreased (2.6 vs 4.4 pg/ml) and MMP-3 (26 vs 23.5 ng/ml) increased. Adipose tissue expression of mRNAs (arbitrary units) for MCP-1 (3585 vs 2020, p=0.06), PPAR-γ (1257 vs 1166), PAI-1 (823 vs 338, p=0.08) increased, whereas interleukin-8 (163 vs 312), TNF-α (75 vs 94) and p16 (129 vs 169) decreased. Cellular senescence-associated beta galactosidase activity (2.2% vs 3.6%, p=0.18) tended to decrease. We observed some correlation between some senescence markers and physical performance but no improvement in frailty with rapamycin was noted. (NCT01649960).

Extracellular matrix molecules and follicle morphogenesis in ovine skin

Chondroitin sulphate, fibronectin, laminin and the hyaluronan receptor, CD44, were localized in ovine skin during follicle morphogenesis. Prior to initiation, chondroitin sulphate was detected in the mesenchyme adjacent to the dermal-epidermal junction and showed an approximately regular periodicity in staining intensity. With the appearance of follicle primordia, the more strongly stained regions of the matrix were associated with mesenchymal condensations. During later development and in the mature follicle, staining was localized to the matrices of cells of the dermal sheath and papilla. CD44 was also localized in the mesenchymal condensations at follicle initiation and, subsequently, in the dermal sheath. Fibronectin staining was confined to the mesenchyme prior to follicle formation and became associated with presumptive papilla and dermal sheath cells during follicle formation and maturation. Fibronectin antisera detected an approximately 220 kDa protein in western blots of adult and fetal skin. An additional band of 150 kDa was also observed prior to follicle initiation. In contrast, laminin was predominantly restricted to the basal laminae of developing and mature follicles. The aggregative behaviour of ovine papilla cells was examined in vitro. The number and size of aggregates were not affected by inclusion of chondroitin sulphate or fibronectin in the culture medium, but both increased in the presence of hyaluronidase. Chondroitinase had the opposite effect and beta-D-xyloside completely abolished aggregative behaviour. In conclusion, the appearance of certain matrix molecules may presage morphogenetic movements of cells at follicle initiation and regulate patterns of follicle distribution in skin during fetal life.

Epitope mapping of the transforming growth factor-beta superfamily protein, macrophage inhibitory cytokine-1 (MIC-1): identification of at least five distinct epitope specificities

Macrophage inhibitory cytokine-1 (MIC-1) is a divergent member of the transforming growth factor-beta (TGF-beta) superfamily whose increased expression is associated with macrophage activation and which is expressed highly in placenta as compared to other tissues. There are two known allelic forms of human MIC-1 due an amino acid substitution at position 6 of the mature protein. We have raised four monoclonal antibodies (MAbs) and one polyclonal antiserum to the mature protein region of human MIC-1 and have used an extensive panel of MIC-1 relatives, mutants, and chimeras to map their epitopes. None of the MAbs were able to cross-react with either the murine homologue of MIC-1 or with hTGF-beta1, and all of the MAb epitopes were conformation-dependent. A distinct cross-reactivity pattern with the various antigens was observed for each of the monoclonal and polyclonal antibodies suggesting the presence of at least five immunogenic regions on the MIC-1 surface. One of the MAbs is directed against the amino terminus of the protein and can distinguish between the two allelic forms of MIC-1. The epitopes for the other three MAbs were located near the tips of the so-called "fingers" of the protein and appeared to be partially overlapping as each involved amino acids in the region 24-37. In one case, it was possible to mutate murine MIC-1 so that it could be recognized by one of the MAbs. Finally, the use of another mutant in which Cys 77 was replaced by serine enabled confirmation of the location of the MIC-1 interchain disulfide bond.

The transforming growth factor-ss superfamily cytokine macrophage inhibitory cytokine-1 is present in high concentrations in the serum of pregnant women

Macrophage inhibitory cytokine-1 (MIC-1) is a recently described divergent member of the transforming growth factor-ss superfamily. MIC-1 transcription up-regulation is associated with macrophage activation, and this observation led to its cloning. Northern blots indicate that MIC-1 is also present in human placenta. A sensitive sandwich enzyme-linked immunosorbent assay for the quantification of MIC-1 was developed and used to examine the role of this cytokine in pregnancy. High levels of MIC-1 are present in the sera of pregnant women. The level rises substantially with progress of gestation. MIC-1 can also be detected, in large amounts, in amniotic fluid and placental extracts. In addition, the BeWo placental trophoblastic cell line was found to constitutively express the MIC-1 transcript and secrete large amounts of MIC-1. These findings suggest that the placental trophoblast is a major source of the MIC-1 present in maternal serum and amniotic fluid. We suggest that MIC-1 may promote fetal survival by suppressing the production of maternally derived proinflammatory cytokines within the uterus.

The propeptide of macrophage inhibitory cytokine (MIC-1), a TGF-beta superfamily member, acts as a quality control determinant for correctly folded MIC-1

Macrophage inhibitory cytokine (MIC-1), a divergent member of the transforming growth factor-beta (TGF-beta) superfamily and activation associated cytokine, is secreted as a 28 kDa dimer. To understand its secretion, we examined its processing in MIC-1-transfected Chinese hamster ovary cells. Mature MIC-1 dimer arises post-endoplasmic reticulum (ER) by proteolytic cleavage of dimeric pro-MIC-1 precursor at a furin-like site. Unlike previously characterized TGF-beta superfamily members, MIC-1 dimers are also secreted in constructs lacking the propeptide. A clue to the function of the propeptide came from the observation that a range of proteasome inhibitors, including lactacystin and MG132, cause major increases in levels of undimerized pro-MIC-1 precursor. There was no effect of proteasome inhibitors on cells expressing mature MIC-1 without the propeptide, suggesting that the propeptide can signal misfolding of MIC-1, leading to proteasomal degradation. Deletion mutagenesis showed the N-terminal 28 amino acids of the propeptide are necessary for proteasomal degradation. This is the first demonstration, to our knowledge, of a quality control function in a propeptide domain of a secretory protein and represents an additional mechanism to ensure correct folding of proteins leaving the ER.

The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease

CONTEXT

Acute aortic dissection is a life-threatening medical emergency associated with high rates of morbidity and mortality. Data are limited regarding the effect of recent imaging and therapeutic advances on patient care and outcomes in this setting.

OBJECTIVE

To assess the presentation, management, and outcomes of acute aortic dissection.

DESIGN

Case series with patients enrolled between January 1996 and December 1998. Data were collected at presentation and by physician review of hospital records.

SETTING

The International Registry of Acute Aortic Dissection, consisting of 12 international referral centers.

PARTICIPANTS

A total of 464 patients (mean age, 63 years; 65.3% male), 62.3% of whom had type A dissection.

MAIN OUTCOME MEASURES

Presenting history, physical findings, management, and mortality, as assessed by history and physician review of hospital records.

RESULTS

While sudden onset of severe sharp pain was the single most common presenting complaint, the clinical presentation was diverse. Classic physical findings such as aortic regurgitation and pulse deficit were noted in only 31.6% and 15.1% of patients, respectively, and initial chest radiograph and electrocardiogram were frequently not helpful (no abnormalities were noted in 12.4% and 31.3% of patients, respectively). Computed tomography was the initial imaging modality used in 61.1%. Overall in-hospital mortality was 27.4%. Mortality of patients with type A dissection managed surgically was 26%; among those not receiving surgery (typically because of advanced age and comorbidity), mortality was 58%. Mortality of patients with type B dissection treated medically was 10.7%. Surgery was performed in 20% of patients with type B dissection; mortality in this group was 31.4%.

CONCLUSIONS

Acute aortic dissection presents with a wide range of manifestations, and classic findings are often absent. A high clinical index of suspicion is necessary. Despite recent advances, in-hospital mortality rates remain high. Our data support the need for continued improvement in prevention, diagnosis, and management of acute aortic dissection.

MIC-1 is a novel TGF-beta superfamily cytokine associated with macrophage activation

As part of a study to identify novel genes associated with macrophage activation, we have cloned a new member of the transforming growth factor beta (TGF-beta) superfamily designated macrophage inhibitory cytokine 1 (MIC-1). MIC-1 is synthesized as a 62-kDa intracellular protein, which, after cleavage by a furin like protease, is secreted as a 25-kDa disulfide-linked dimeric protein. Sequence analysis indicates that it does not cluster within any existing TGF-beta families, suggesting it may be the first member of a new grouping within the TGF-beta superfamily. Tissue Northern blots show that MIC-1 transcripts are only found abundantly in placenta, although smaller amounts are seen in a limited number of other adult and fetal tissues. MIC-1 is not expressed in resting macrophages but is induced by a number of different activation agents, including phorbol myristate acetate, interleukin 1, tumor necrosis factor alpha, and macrophage colony-stimulating factor but not by lipopolysaccharide or interferon-gamma. We have hypothesized that it may be an autocrine inhibitor of macrophage activation but its major biological role is still uncertain.

Viable Cryptosporidium parvum oocysts exposed to chlorine or other oxidising conditions may lack identifying epitopes

The intestinal protozoan parasite Cryptosporidium parvum is a known cause of water-borne disease in humans. The detection of Cryptosporidium oocysts in water samples relies upon the use of fluorescently labelled antibodies, preferably using flow cytometry and epifluorescence microscopy. Here we demonstrate that four commercially available antibodies recognise a similar set of immunodominant epitopes on the oocyst wall. These epitopes appear to be carbohydrate in nature and are labile to chlorine treatment and oxidising conditions. Sodium hypochlorite and sodium meta-periodate reduced the ability of the antibodies to detect Cryptosporidium oocysts. Damage to the epitopes did not necessarily reduce the viability of oocysts. This finding may be important for the water industry, where naturally occurring oxidising conditions or sanitizing treatments could produce viable oocysts that are undetectable using standard protocols.

Gender differences in the renal nitric oxide (NO) system: dissociation between expression of endothelial NO synthase and renal hemodynamic response to NO synthase inhibition

Many studies have shown that nitric oxide (NO) production is higher in the systemic vasculature of females than males and is stimulated during pregnancy, a high estrogen state. The present study was performed in rats to determine whether females had a greater expression of endothelial NO synthase (eNOS) in kidneys than did males; whether there were gender differences in the excretion of NO metabolites, nitrate/nitrite; and whether there were gender differences in the renal hemodynamic response to NO synthase inhibition. The renal levels of eNOS mRNA (as measured by ribonuclease protection assays) and protein (as measured by Western blot) were 80% higher in kidneys from females than from males (P < .001). Urinary excretion of NO metabolites, nitrate/nitrite, were not different between males and females. To inhibit eNOS, rats were treated with nitro-L-arginine methyl ester (L-NAME, 3 to 4 mg/kg/day) for 2 weeks. Although there were no differences in basal renal hemodynamics between males and females, when factored for kidney weight, chronic L-NAME increased renal vascular resistance by 130% in males but by only 60% in females, and decreased renal plasma flow by 40% in males but had no effect in females. These data show that although the renal levels of eNOS mRNA and protein are higher in females than in males, the renal vasculature of males is more responsive to NO synthase inhibition. The data suggest that the renal vasculature of males may be more dependent on NO than is the renal vasculature in females.

MIC-1, a novel macrophage inhibitory cytokine, is a divergent member of the TGF-beta superfamily

Macrophages play a key role in both normal and pathological processes involving immune and inflammatory responses, to a large extent through their capacity to secrete a wide range of biologically active molecules. To identify some of these as yet not characterized molecules, we have used a subtraction cloning approach designed to identify genes expressed in association with macrophage activation. One of these genes, designated macrophage inhibitory cytokine 1 (MIC-1), encodes a protein that bears the structural characteristics of a transforming growth factor beta (TGF-beta) superfamily cytokine. Although it belongs to this superfamily, it has no strong homology to existing families, indicating that it is a divergent member that may represent the first of a new family within this grouping. Expression of MIC-1 mRNA in monocytoid cells is up-regulated by a variety of stimuli associated with activation, including interleukin 1beta, tumor necrosis factor alpha (TNF-alpha), interleukin 2, and macrophage colony-stimulating factor but not interferon gamma, or lipopolysaccharide (LPS). Its expression is also increased by TGF-beta. Expression of MIC-1 in CHO cells results in the proteolytic cleavage of the propeptide and secretion of a cysteine-rich dimeric protein of Mr 25 kDa. Purified recombinant MIC-1 is able to inhibit lipopolysaccharide -induced macrophage TNF-alpha production, suggesting that MIC-1 acts in macrophages as an autocrine regulatory molecule. Its production in response to secreted proinflammatory cytokines and TGF-beta may serve to limit the later phases of macrophage activation.

The interaction of hedamycin and DC92-B in a sequence selective manner with DNA in intact human cells

The sequence specificity of the pluramycin antibiotics hedamycin and DC92-B, was established in intact human cells using a linear amplification system. In this system an oligonucleotide primer is extended by Taq DNA polymerase up to a damage site. The products are run on a DNA sequencing gel and the damage can be determined to the exact base pair. The human repetitive alpha RI DNA was used as the target DNA sequence for these experiments. It was found that G residues were the main site of adduct formation, for both hedamycin and DC92-B. The sequences 5'-TGT and 5'-CGT were the most intense sites of DNA damage. A comparison of the DNA damage intensity in intact cells and purified DNA revealed that the sequence position of adduct formation was very similar in the two environments. However, a densitometric comparison of the damage intensity in the two environments revealed significant differences. Two regions were found (120 and 130 bp in length) where the damage intensity was relatively lower in intact cells compared to purified DNA. But at the boundaries of these sequences, there were regions (approx. 50-60 bp long) that were relatively more damaged in intact cells compared to purified DNA. One explanation of this phenomenon is the presence of a protecting nucleosome core on each of the 120/130 bp regions and flanking nucleosome linker regions of 50-60 bp. This postulated sequence phasing of the nucleosomes corresponds almost exactly with the major nucleosome phasing found in African green monkey cells. Also the centromere protein B binding site is found in the border region between the nucleosome core and linker DNA regions. Hedamycin and DC92-B produced nearly identical results in this human cell system.

Comparison of the sequence selectivity of the DNA-alkylating pluramycin antitumour antibiotics DC92-B and hedamycin

The sequence selectivity of DNA alkylation by the recently isolated pluramycin antitumour antibiotic DC92-B has been investigated using two methods: a piperidine-induced strand-breaking procedure and a Taq DNA polymerase/linear amplification method. These techniques reveal that guanines are the most reactive sites for alkylation and that the level of adduct formation at these sites is clearly sequence dependent. The highest levels of alkylation occurred at isolated guanines located in 5'-CGT sequences and also at the 5'-G in some 5'-CGG sequences. Isolated guanines in 5'-TGT sequences were also quite reactive. We have also re-examined, in parallel, the sequence selectivity of binding of the structurally-related compound hedamycin: the first known example of a bis(epoxide)-containing, DNA-alkylating pluramycin. Our studies included a more extensive sequence analysis of hedamycin binding than that previously reported and we are able, therefore, to define more precisely the sequence preference. Despite significant differences in the stereochemistry and substitution of their bis(epoxide) sidechains, hedamycin and DC92-B exhibited very similar sequence selectivities in our assays.

Age-related characteristics of ambulatory blood pressure load and mean blood pressure in normotensive subjects

Ambulatory blood pressure monitoring has become increasingly popular for diagnosing and treating hypertension. However, data from normotensive subjects are needed for interpretation of hypertensive readings. Ambulatory blood pressure was monitored in 126 normotensive subjects (age range, 20 to 84 years). Mean systolic and diastolic blood pressure and blood pressure loads (percentage of systolic readings greater than 140 mm Hg and diastolic readings greater than 90 mm Hg) were obtained and interpreted. Mean awake systolic and diastolic pressures ranged from 125 +/- 10 to 137 +/- 17 mm Hg and 70 +/- 8 to 71 +/- 9 mm Hg, respectively. The systolic and diastolic trends of subjects' blood pressures taken during office visits and the 24-hour measurements were similar. Ranges for systolic and diastolic blood pressure loads from youngest to oldest ages were 9% +/- 14% to 25% +/- 20% and 3% +/- 7% to 4% +/- 7%, respectively. A comparison of blood pressure means from our sample that were taken during office visits and blood pressure means from a 2122-patient community survey demonstrated that our sample was reflective of an unselected population.

Reproducibility of ambulatory blood pressure load

Twenty-two hypertensive patients were monitored during two separate drug-free occasions with a Del Mar Avionics ambulatory device. Blood pressure loads (percentage of systolic and diastolic readings more than 140 and 90 mmHg, respectively) and mean BP were measured both to determine their reproducibility and to examine how they correlate with each other. The systolic and diastolic mean awake BPs for day 1 and day 2 were 140/93 mmHg and 140/91 mmHg, respectively, and BP loads were 45%/55% and 43%/54%. Moreover, mean BP loads correlated highly (r = 0.93) with mean BP values taken on the same day. Both ambulatory mean SBP and BP load were highly reproducible (r = 0.87 and 0.80, respectively, during the awake hours), and mean DBP and load were fairly reproducible (r = 0.59 and 0.39, respectively, during the awake hours). Clinically, however, both were consistent from day 1 to day 2. Mean and individual standard deviations also were reproducible for both systolic and diastolic pressures and loads.

Antihypertensive effects of a new sustained-release formulation of nifedipine

The blood pressure response to a new sustained-release formulation of nifedipine was evaluated in an 8-week, double-blind, placebo-controlled study. Twenty-nine patients with mild essential hypertension were randomized to receive placebo (N = 9), 30 mg nifedipine (N = 10), or 60 mg nifedipine (N = 10). During treatment, 30-mg and 60-mg doses of nifedipine administered once daily decreased office blood pressures from 137/98 +/- 8/2 mm Hg and 141/98 +/- 15/2 mm Hg at baseline, respectively, to 126/89 +/- 9/7 mm Hg and 126/86 +/- 6/7 mm Hg (P less than .005). Noninvasive automatic ambulatory blood pressure monitoring demonstrated a marginally significant (P less than .10) reduction in the mean 24-hour blood pressure of 2/6 +/- 8/8 mm Hg and 5/6 +/- 9/9 mm Hg for patients taking 30 mg and 60 mg nifedipine once daily, respectively. Diastolic blood pressure load (the percentage of ambulatory diastolic blood pressure readings greater than 90 mm Hg) during 24 hours was decreased by 41% and 35%, with 30 mg and 60 mg nifedipine administered once daily, respectively. No significant dose response to nifedipine at these dose levels was observed. Although the once-daily formulation of nifedipine achieved effective control of office blood pressure, similar control was not observed in awake and 24-hour periods in all patients.

Office blood pressures in supine, sitting, and standing positions: correlation with ambulatory blood pressures

The variability of casual (office) blood pressure according to position at the time of measurement was investigated in 168 untreated patients with a history of mild to moderate essential hypertension. Two measurements were made in the supine, sitting, and standing positions on each of 2 consecutive days, and 24-hour ambulatory blood pressure monitoring was performed. The mean supine, sitting, and standing blood pressures were 146 +/- 15/91 +/- 7, 144 +/- 15/96 +/- 8, and 149 +/- 17/103 +/- 7 mm Hg, respectively. Diastolic blood pressures were significantly different from each other (P less than 0.0001). Supine and sitting systolic blood pressures were not different, but they were different from standing blood pressure (P less than 0.0001). The mean of all three positions (overall blood pressure) was 146 +/- 15/96 +/- 7 mm Hg. Supine, sitting, standing, and overall diastolic blood pressure means were 90 mm Hg or more in 88, 133, 164, and 133 patients, respectively. The mean awake ambulatory and 24-hour ambulatory blood pressures were 143 +/- 16/95 +/- 7 and 138 +/- 16/92 +/- 8 mm Hg, respectively, and diastolic blood pressures were 90 mm Hg or more in 121 and 88 patients, respectively. The correlation of office blood pressure with ambulatory blood pressure varied according to office position and was 0.76 to 0.82 (P less than 0.0001) for systolic blood pressure and 0.60 to 0.69 (P less than 0.0001) for diastolic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Passive immunisation of children with bovine colostrum containing antibodies to human rotavirus

The efficacy of a 10-day course of bovine colostrum with high antibody titre against the four known human rotavirus serotypes in protecting children against rotavirus infection was examined in patients admitted to hospital. Children aged 3 to 15 months were blocked in pairs according to ward accommodation (ie, isolation or open area). Each block contained 1 treated and 1 control child. The allocation to treatment or control (an artificial infant formula) was randomised. 9 of 65 control children but none of 55 treated children acquired rotavirus infection during the treatment period (p less than 0.001). The importance of protecting against rotavirus infection was highlighted by the fact that parents of symptomatic rotavirus-positive children sought medical attention seven times more often than did parents of symptomatic rotavirus-negative children (p less than 0.05).

Passive immunisation of children with bovine colostrum containing antibodies to human rotavirus

The efficacy of a 10-day course of bovine colostrum with high antibody titre against the four known human rotavirus serotypes in protecting children against rotavirus infection was examined in patients admitted to hospital. Children aged 3 to 15 months were blocked in pairs according to ward accommodation (ie, isolation or open area). Each block contained 1 treated and 1 control child. The allocation to treatment or control (an artificial infant formula) was randomised. 9 of 65 control children but none of 55 treated children acquired rotavirus infection during the treatment period (p less than 0.001). The importance of protecting against rotavirus infection was highlighted by the fact that parents of symptomatic rotavirus-positive children sought medical attention seven times more often than did parents of symptomatic rotavirus-negative children (p less than 0.05).

Current practice in health promotion

Progress in health promotion and preventive programme planning is limited by a lack of data on the development of current activities. A cross sectional survey of hospitals, community health centres, and other health agencies in New South Wales was therefore undertaken to determine the nature and extent of health promotion programmes being conducted in the period July to December 1983. A subsample of 1198 preventive programmes in child and family health was identified, making up 26% of all programmes operating in this period. Results indicate that three major types of programme are being conducted in child health. These are in the areas of (1) parent education and support, (2) school health education, including drug and alcohol education and personal development, and (3) child safety and first aid. Although the nature of these programmes generally corresponds with current thinking on what priorities in health promotion should be, results also indicate that evaluation of these programmes is limited. Most programmes assess only what participants think of the programme rather than assessing changes in knowledge, attitude, behaviour, or health status. Improvements in evaluation practice are required if preventive intervention programmes are to undertake seriously the task of altering the pattern of diseases and problems in childhood and adolescence.

An easily applied and removed dry annular suction electrode

A new type of self-retaining dry metal electrode for the electrocardiogram (ECG) is described which adheres to the skin by the application of negative pressure to an annulus surrounding the electrode, which is a bare silver. Data are presented for the factors which govern the adherence to the skin and the range of initial impedance and the values obtained at 2, 5, 10 and 20 minutes and with tap water under the electrodes. The initial impedance is usually high (0.18 to 10 megohms) and decreases progressively with time. Tap water placed under the electrodes dramatically reduces the initial range of impedance. Such electrodes, when used with an amplifier with an adequately high input impedance, can be used for recording electrocardiograms in a variety of situations.

Electrical dose for ventricular defibrillation of large and small animals using precordial electrodes

Electrical ventricular defibrillation of heavy subjects (over 100 kg body weight) is uncommon for the human or any animal species. This paper reports trans-chest ventricular defibrillation of subjects ranging in weight from 2.3 to 340 kg using conventional defibrillation current (heavily damped sine wave) of 0.3-30 ms duration. It was found that a body weight-to-electrical-shock strength relationship exists and can be expressed in terms of either electrical energy or peak current. For the duration of current pulse used clinically (3-10 ms), the relationship between energy requirement and body weight is expressed by the equation U = 0.73 W(1.52), where U is the energy in W.s and W is the body weight in kilograms. The current relationship is I = 1.87 W(0.88) where I is the peak current in amperes and W is the body weight in kilograms. The energy dose is somewhat more species and weight dependent and ranges from 0.5 to 10 W.s/kg (0.23-4.5 W.s/lb). The data obtained indicate that the peak current dose is virtually species and weight independent and is therefore a better indicator than energy for electrical defibrillation with precordial electrodes. In the duration range of 3-10 ms, the electrical dose is very nearly 1 A/kg of body weight (0.45 A/lb).

Ventricular Defibrillation of a 341 kg Horse Using Precordial Electrodes

Using a specially constructed 5000 watt-second defibrillator, trans-chest ventricular defibrillation was achieved in a 341 kg horse. Minimum peak electrical current flow used to defibrillate was 280 amperes; maximum peak current was 300 amperes. Circulatory support by external cardiac compression was necessary for a 25 minute period after defibrillation. Resumption of cardiac function was achieved only after intravenous administration of epinephine, calcium chloride and dexamethazone.To the authors' knowledge, this is the largest animal in which electrical ventricular defibrillation has been reported.