Verapamil induced ventricular hypertrophy in conscious dogs.

Verapamil is used clinically in the treatment of various cardiac diseases including hypertrophic cardiomyopathy. Its long term effects on ventricular mass are not well known. In 11 conscious dogs heart rate, aortic and left ventricular pressures, cardiac output, a methoxamine induced stress ventricular function test and left ventriculography were performed. These variables were measured prior to and following a mean 7.2 month infusion of verapamil at 0.005 or 0.01 mg.kg-1.min-1 using a subcutaneously implanted pump. Resting haemodynamic variables and left ventricular ejection fraction [60(SD 6) v 55(6)%] were unchanged between baseline and chronic verapamil studies, but the slope of the methoxamine induced stress ventricular function test decreased from 3.9(0.8) to 2.1 (1.3). After verapamil was discontinued the mean slope of the stress ventricular function test returned to the baseline 4.0(1.7). Total ventricular weight increased 22% from 176.1(17.5) g.m-2 in controls to 215.6(29.5) g.m-2 (p less than 0.01) in the verapamil animals. The right ventricular weight increased 25% from 46(5.9) to 57.6(9.1) g.m-2 (p less than 0.01); the septum weight increased 26% from 42.5(4.1) to 53.7(7.2) g.m-2 (p less than 0.001); and the left ventricular free wall weight increased 19% from 87.4(9.8) to 103.9(15.7) g.m-2 (p less than 0.01). The increase in ventricular weights was not due to fibrosis or oedema since hydroxyproline contents and wet/dry ratios were not increased. In conclusion, a chronic infusion of verapamil in conscious dogs caused no change in resting haemodynamic variables but produced reversible depression of stress ventricular function and biventricular and septal hypertrophy.

Achondrogenesis type I: delineation of further heterogeneity and identification of two distinct subgroups.

Achondrogenesis has traditionally been divided into type I (Parenti-Fraccaro) and type II (Langer-Saldino). We studied the clinical, radiologic, and morphologic features of 17 cases previously diagnosed as achondrogenesis type I to define whether there is even further heterogeneity. On radiographic analysis, two distinct groups of patients were defined based on the presence or absence of rib fractures and ossification of the vertebral pedicles, ischium, and fibula. Two distinct chondroosseous morphologic patterns were observed that directly correlated with the radiographic grouping. One group had round vacuolated chondrocytes with inclusion bodies; the other had collagenous rings around the chondrocytes. We conclude that achondrogenesis type I (Parenti-Fraccaro) consists of two distinct disorders: type IA, which corresponds to the cases originally published by Houston et al. and Harris et al., and type IB, which corresponds to the case originally published by Fraccaro. Analysis of Parenti's case suggests the diagnosis of achondrogenesis type II. All three types of achondrogenesis appear to be inherited as autosomal recessive traits.

Dyssegmental dysplasias: clinical, radiographic, and morphologic evidence of heterogeneity.

The dyssegmental dysplasias are lethal forms of neonatal short-limbed dwarfism in which vertebral segmentation defects and short, thick, bowed long bones are the prominent radiographic features. Clinically, unusual facies, short neck, narrow thorax, cleft palate, and reduced joint mobility are commonly seen. To date, 18 cases of dyssegmental dysplasia have been reported. Reports of three pairs of affected sibs suggest autosomal recessive inheritance. We have studied eight additional cases of dyssegmental dysplasia, including one pair of affected sibs. Clinical, radiographic, and histologic examination of these new cases and review of the literature demonstrates the presence of at least two distinct forms of dyssegmental dysplasia. The milder form, "dyssegmental dysplasia, type Rolland-Desbuquois," is characterized clinically by frequent survival beyond the newborn period and by distinct radiographic changes resembling Kniest dysplasia. The severe form, "dyssegmental dysplasia, type Silverman-Handmarker," is characterized by stillbirth or death within the first few days of life and by distinct and more severe radiographic changes. In addition, we have demonstrated chondro-osseous morphologic differences between the two disorders by light and electron microscopy. We conclude that there are at least two forms of dyssegmental dysplasia, each autosomal recessive, which can be delineated on clinical, radiographic and morphologic grounds.

Prenatal diagnosis of osteogenesis imperfecta type III.

Ultrasonographic and radiographic evaluation of a fetus at risk for osteogenesis imperfecta (O.I) type III was performed. Real-time ultrasound measurements at 15 weeks gestation were interpreted as normal, but at 20 and 22 weeks of gestation revealed marked shortening of the long bones and deformity of the femurs. The findings were confirmed by fetal radiography at 22 weeks gestation. Radiographic and histologic changes characteristic of O.I. were observed in the aborted fetus. Thus the antenatal manifestations of O.I. type III maybe severe enough to make prenatal diagnosis possible in the second trimester for families at risk for recurrence of this disorder.

A new skeletal dysplasia: clinical, radiologic, and pathologic findings.

Two siblings, one male and one female, were noted to have a distinct skeletal dysplasia. The clinical and radiographic features resemble those observed in Kniest dysplasia and Rolland-Desbuquois syndrome, but important differences were noted. Specifically, these two patients have microstomia, "pursed" lips, and ectopia lentis, and their radiographs reveal no coronal clefts. Chondro-osseous features also differ from those observed in either of the other disorders. Scattered dense patches consisting of collagen fibers 10 to 30 times broader than normal are seen scattered throughout the cartilage matrix; the "Swiss cheese" appearance characteristic of Kniest dysplasia is not observed. These patients appear to have a new skeletal dysplasia, most likely inherited in an autosomal recessive fashion.

Myofibrillar disarray produced in normal hearts by chronic electrical pacing.

Myofibrillar disarray has been observed in various normal, experimental, and pathologic conditions of the heart. In order to elucidate the common denominator involved in the development of disarray, we undertook the present study to test the hypothesis that myofibrillar disarray can be produced in the normal heart as a result of altering myocardial stress vectors. In the heart, the vectors associated with the patterns of contraction are determined by the sequence of depolarization. In order to alter this sequence, the conduction system of 12 normal dogs was interrupted by the production of complete atrioventricular block. After 3 months of electronic pacing of the right ventricular apex at 70 bpm, myofibrillar disarray was observed in 9 out of 12 of these hearts. In matched tissue samples from 12 control dogs, myofibrillar disarray was not observed. We conclude that myofibrillar disarray may be produced by abnormal stress vectors resulting from alterations in the sequence of depolarization, and therefore the pattern of contraction. We believe this to represent a unifying concept to explain the development of myofibrillar disarray observed in a variety of conditions.

Histologic and ultrastructural studies on the mineralization process in hypophosphatasia.

Chondroosseous tissue from six infants with infantile hypophosphatasia and six control infants were studied by light, transmission, and scanning electron microscopy. Alkaline phosphatase histochemical reaction of the growth plate was studied in two infants and was greatly reduced when compared to two control infants. Hypertrophic chondrocytes were increased in number with persisting cartilage islets in the metaphysis. In five of the six cases studied, chondrocytes and intercartilagenous intercellular chondroid matrix appeared ultrastructurally normal. Matrix vesicle distribution was similar to that of control subjects, but they were associated with few mineral crystals. In two infants, the matrix vesicles were alkaline phosphatase nonreactive. In the calcifying zone of the growth plate and in the newly formed metaphyseal trabecular bone, cartilagenous calcospherites often were small and the orientation of crystals was nonradial when compared to that of control infants. The mineralization of diaphyseal bone appeared normal. It seems that matrix vesicles are present in hypophosphatasia and that the impaired mineralization of cartilage is due primarily to the deficiency of alkaline phosphatase. In spite of the lack of alkaline phosphatase, secondary mineralization of bone which is not mediated by matrix vesicles was normal.

Endocardial and transcutaneous cardiac pacing, calcium chloride, and epinephrine in postcountershock asystole and bradycardias.

Clinically, asystole or a bradyarrhythmia may follow countershock of ventricular fibrillation (VF) in up to 40% of attempts. This study evaluated the effects of artificial cardiac pacing, calcium chloride (CaCl2), and epinephrine in postcountershock asystole/bradycardia. Micromanometer catheters were positioned in the aorta (Ao) and right atrium (RA) of ten dogs and VF induced by right ventricular (RV) stimulation. After 2 min of VF, a 400-J countershock was given. In six animals, asystole or a pulseless bradyarrhythmia followed one countershock. In four animals, up to three countershocks were needed to terminate VF and resulted in asystole or a pulseless bradyarrhythmia. Thirty seconds after termination of VF, cardiac pacing was begun in all animals using conventional RV endocardial pacing (RVEP) or a transcutaneous transthoracic pacing (TTP) technique. RVEP and TTP produced ventricular depolarizations, but electrical capture was never associated with Ao pressure fluctuations. After 2 min of pacing, CaCl2 was given and chest compressions and artificial ventilations (CPR) initiated. CaCl2 had no effect on CPR pressures. After 2 min of CPR, RVEP and TTP were again studied; capture without Ao pressure fluctuations was seen in all animals. Epinephrine was then given and CPR reinstituted. Epinephrine produced a significant increase in CPR Ao systolic pressure (58 +/- 13 to 84 +/- 24 mm Hg, p less than .001) and end-diastolic coronary perfusion pressure (Ao-RA) (9 +/- 4 to 34 +/- 8 mm Hg, p less than .001). Within 94 +/- 53 sec after epinephrine, spontaneous circulation was restored in eight animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of mesenchyme-like tissue in the pathogenesis of thanatophoric dysplasia.

We have studied the light microscopic, transmission, and scanning electron microscopic (SEM) findings in 13 cases of thanathophoric dysplasia (TD) and 4 control infants. In the TD growth plate, areas with less abnormal cartilage and bone alternated with areas of severely abnormal cartilage and bone. These latter abnormal areas were always found around tongues of apparent mesenchymal tissue that appeared to penetrate from the investing perichondrium and periosteum. The ultrastructure of the less abnormal areas was similar to that of the control infants, including cell and matrix structure as well as mineralization. The abnormal cartilage and bone had many ultrastructural abnormalities that were also found in the adjacent mesenchymal tissue. The mesenchymal cells, adjacent chondrocytes, and osteoblasts contained dilated endoplasmic reticulum and moderately large intracytoplasmic vacuoles. In the area adjacent to the cartilage, the matrix of the apparent mesenchyme contained thin collagen fibers and proteoglycan granules, whereas the matrix adjacent to the bone contained thick bundles of short collagen fibers. The matrix of the surrounding cartilage and bone resembled the adjacent matrix in the mesenchyme. In addition, many vesicular structures or osmiophilic particles were found in the matrix of the mesenchyme and adjacent cartilage and bone. SEM examination showed normal and abnormal bone trabeculae adjacent to each other. In the abnormal trabeculae, there were large, densely packed osteoblastic and osteocytic lacunae. The calcified collagen fibers had a random orientation, in contrast to the longitudinal orientation in the relatively normal bone. Chemical studies of collagen in the metaphyses of bones from five infants with TD showed a small amount of collagen type III (less than 5%), which was not found in three control infants. Thus, a basic pathogenetic mechanism in the skeletal abnormalities of TD appears to be the focal replacement of the growth plate and periosteum by persisting abnormal mesenchymal-like tissue from which the abnormal bone originates.

Two biochemically distinct populations of histaminocytes separated by isokinetic sedimentation of dispersed rat gastric cells.

Two populations of histaminocytes, with different sedimentation rates (SR), were separated by a computer developed isokinetic gradient using dispersed rat gastric mucosal cells. Histamine content, histidine decarboxylase (HDC) activity and incorporation of radiolabelled histidine metabolites were used to assess the migration of specific cells throughout the gradients. One histaminocyte population, with cells of lower SR, contained high HDC activity and undetectable levels of histamine, whereas the other population, with cells of higher SR, contained lower HDC activity and high concentration of histamine. Both types of histaminocytes incorporated 3H-histidine metabolites. Electron microscopy showed that the fractions containing histaminocytes with lower SR had 3.5 times more endocrine ECL cells than the original population of dispersed fundic cells and lacked A and D cells, whereas the fractions with histaminocytes of higher SR were associated with a 2.7 times higher concentration of A and D cells and with a 7.7 times higher ratio of a variety of partial cells with a distinct mitochondrial morphology. These results are consistent with prior novel information regarding the separation of two populations of rat histaminocytes using different sedimentation techniques.

Fibrochondrogenesis: radiologic and histologic studies.

Fibrochondrogenesis is a distinct, neonatally lethal, short-limb skeletal dysplasia which was first described in a single patient in 1978. We report the radiographic and morphologic studies of 2 additional unrelated stillborn infants with fibrochondrogenesis. This syndrome has distinct radiographic and chondro-osseous morphologic defects different from those seen in the other known skeletal dysplasias. The long bones are short and dumbbell-shaped with metaphyseal flare. The spine is platyspondylic with superior-inferior clefting defects, and the ribs are short and distally cupped. The growth-plate cartilage is grossly disorganized and has a densely fibrous collagenous matrix when examined by light and electron microscopy. Light, transmission, and scanning electron microscopy shows diaphyseal and metaphyseal trabecular bone to be normal.

Anetoderma: biochemical and ultrastructural demonstration of an elastin defect in the skin of three patients.

Three patients with localized cutaneous lesions characteristic of anetoderma were studied. Clinically, the onset of the disease was between the ages of 17 and 25, and numerous flaccid, saclike skin lesions developed over several subsequent years. Histologically, the lesions were characterized by paucity and fragmentation of the elastic fibers. Electron microscopy demonstrated that the elastic fibers, both in papillary and deep reticular dermis in the lesional skin, were fragmented and irregular in appearance. The concentration of elastin, determined by a radioimmunoassay of desmosine, an elastin-specific cross-link compound, was markedly reduced in the lesions, as compared with unaffected skin from the same patients or with normal skin from unrelated control subjects. In contrast, the concentrations of hydroxyproline, an index of collagen, or deoxyribonucleic acid (DNA), a measure of cellularity, were not changed in the lesions. Thus, the results indicate that in the three patients studied, the elastic fibers are defective and reduced in quantity. These observations suggest that the deficiency of elastin in the dermis may lead to development of the cutaneous lesions of anetoderma.

Biological system interactions.

Mathematical modeling of cellular population growth, interconnected subsystems of the body, blood flow, and numerous other complex biological systems problems involves nonlinearities and generally randomness as well. Such problems have been dealt with by mathematical methods often changing the actual model to make it tractable. The method presented in this paper (and referenced works) allows much more physically realistic solutions.

A distinct chondrodysplasia resembling Kniest dysplasia: clinical, roentgenographic, histologic, and ultrastructural findings.

Two sibs, one girl and one boy, were observed in infancy with a severe lethal skeletal dysplasia syndrome that radiologically and histologically resembled Kniest dysplasia but clearly differed in clinical course and inheritance. Kniest dysplasia is a nonlethal syndrome, whereas both of these infants died in the neonatal period. Kniest dysplasia appears to be inherited as an autosomal dominant trait; the likely transmission in this family was autosomal recessive. Roentgenograms revealed dumbbell-shaped long bones superficially similar to Kniest dysplasia, but with markedly shortened diaphyses and metaphyseal irregularities. Chondro-osseous morphology demonstrated a superficially similar foamy "Swiss cheese" appearance to the cartilage matrix, as seen in Kniest dysplasia, but there were distinctly different changes in the growth plate and resting cartilage. Ultrastructurally, the chondrocytic endoplasmic reticulum was found to have an appearance different from that observed in either normal or Kniest cartilage. These cases likely represent a distinct chondrodysplasia.

Wound healing: biological effects of Nd:YAG laser on collagen metabolism in pig skin in comparison to thermal burn.

Pig skin was treated with the Nd:YAG laser at 1,060 nm or electrocautery, at energy densities of 649 +/- 20 J/cm2 and 612 J/cm2, respectively. Biopsies of treated areas and of normal skin were performed at 7, 14, and 60 days after treatment and processed for histology, electron microscopy and biochemical assays. Wound healing, as shown histologically, was similar in both treated groups. Depth of injury appeared to reach reticular dermis at day 7 in each treated group. However, thermal burn was more destructive of regular collagen, whereas the laser appeared to damage deep dermal blood vessels without destroying surrounding connective tissue. Biochemical assays revealed increased collagen production and increased collagenolytic activity 7 days after laser injury. However, by day 60, there was a reduction in total collagen content in laser treated skin below that of normal skin, which correlated with decreased collagen synthesis and unchanged collagenolytic activity. In burn specimens there was an initial decrease in total collagen content which reverted to normal by day 60. Active collagen degradation occurred at all 3 time points, but a marked increase in synthetic activity occurred as the burn scar was laid down. Laser treatment resulted in reduction of the amount of collagen below that in burn scarred or normal skin, suggesting that classical scar formation may be inhibited. These results indicate that the Nd:YAG laser may be useful for the treatment of keloids and hypertrophic scars.

Experimental production of complete heart block by electrocoagulation in the closed chest dog.

Methods for producing complete heart block in experimental animals have usually required thoracotomy to gain access to the intracardiac conduction system. A closed chest technique has been developed for producing discrete permanent lesions in the atrioventricular node or His bundle of anesthetized dogs. An insulated transseptal needle is passed through a venous catheter to the right atrium. The exposed tip is pressed into the His bundle and a 30 to 40 joule pulse from a DC defibrillator is transmitted through the needle. This produces a 1 to 3 mm diameter coagulative lesion which permanently destroys the tissue at this point. The process can be repeated until complete heart block is achieved. Our procedure has been successful in 45 of 46 attempts to prepare dogs for acute experiments and, using implanted pacemakers, for chronic studies. We conclude that this closed chest method is a safe and reliable alternative for production of complete heart block requiring thoracotomy, thereby providing an important new means for both acute and chronic experimental studies requiring complete heart block for the improved elucidation of mechanisms and management of cardiovascular diseases.

Technique for serial right and left ventricular endocardial biopsy in dogs.

A method is described for obtaining left and right ventricular endocardial biopsies repeatedly over a period of 3-6 mo in the dog. The left ventricular endocardial biopsy technique consists of the placement of a catheter via the venous route across the atrial septum and into the left ventricle. The biopsy catheter is in turn placed within this transseptal catheter. Tissues obtained by this method were satisfactory for both light and electron microscopic examination. At postmortem examination, only minimal and insignificant damage existed at the biopsy site. Consequently, we recommend this technique for the study of progressive pathologic changes in the endocardium that occur during the course of an experiment which can be identified and quantified in comparison to the control state.