Model of the heart and its applications to the e.c.g.

The human body with the heart as an active electrical source has been modelled by three sets of harmonic polyphase generator voltages or spinning vectors; each set being confined to one of the three standard planes, i.e. the frontal plane, the horizontal plane and the sagittal plane. The equivalent circuit for one of the standard planes, the frontal plane, has been developed and analysed. The identical method of approach for the analysis of e.c.g. voltages in the two other planes has been pointed out and a typical multidimensional case analysis of this model is given. This model has been shown to satisfy a general version of the Burger law and also a general version of the Goldberger augmented lead voltages. The modified Wilson central terminal (w.c.t.) has also been found not to be at the electrical zero of the system. it has further been observed, and confirmed by experiment, that the vector sum of harmonic currents towards the modified w.c.t. is zero, irrespective of the different values of externally connected resistors and without assuming the modified w.c.t. at the electrical zero of the system, i.e. Kirchhoff’s harmonic-current law is satisfied at the modified w.c.t. For equal values of external resistors, the vector sum of the phase voltages and augmented lead voltages also become zero. The model has further been used to study the effect of a number of standard leads placed in the frontal plane while recording the e.c.g., on the maximisation of: (a) the e.c.g. voltages between the standard leads placed over the human body; (b) the e.g.c. voltage between the modified w.c.t. and a reference point on the body; (c) the ratio of the e.c.g. Goldberger voltage to the corresponding phase voltage; and (d) the values of the e.c.g. phase voltages. The effects of the number of electrodes placed in the horizontal and sagittal planes on the respective groups of e.c.g. voltages are discussed. By controlling the number of electrodes in any one of the three standard planes, when the e.c.g. voltages are maximised, it has been shown that the signal-to-noise ratio for those e.c.g. voltages will be increased.     

Pathology of the placenta. II. Malformations of the umbilical cord and the placenta

Malformations of both the umbilical cord and placenta are covered in the second part of this account of placental pathology. Disorders in placental development are subdivided on the basis of the classification published by Vogel (1984). Particular importance is attributed, in this context, to purely morphological differentiation between hydatid and partial mole. Also discussed is the problem of early placental angiomatosis (chorioangiosis, chorioangiomatosis). However, its association with malformations of the placenta seems to be questionable.     

Studies of the hemopoietic microenvironment. VIII. Andrenergic and cholinergic innervation of the murine spleen.

Neurohistochemical techniques were used to confirm morphologically the distribution of adrenergic and cholinergic nerves to the splenic microvasculature. The results form the basis of this report. Using these methods, adrenergic innervation was observed only in the adventitia of arteries and arterioles. No cholinergic innervation was found in this site. No adrenergic or cholinergic innervation could be demonstrated to the channels of the red pulp, venules or veins. These data provided morphological evidence that in the murine spleen only splenic arteries and arterioles are innervated; and these have only an adrenergic innervation.     

The old and the new physical anthropology in the careers of E. A. Hooton and W. M. Krogman

Physical anthropology changed many of its theoretical premises after World War II under the influence of the synthetic theory of evolution. Earnest Albert Hooton (1887–1954) and Wilton Marion Krogman (1903–1987) were excellent examples of leading workers whose research orientations differed, but whose students were important parts of the new consensus. These theoretical innovations undermined the racial morphological typology which underlay much of Hooton's work on racial history, and radiographs of the sizes of bone, marrow, muscle, and fat in the human brachium undermined his work and researches of other constitutionalists and increased the prestige of alternative work on body composition. Krogman, however, initially worked on the growth of the skull and dentition of the great apes and was a leader in human growth studies all his life. He was the most important writer in the United States on forensic applications of human skeletal biology. Since neither growth studies nor forensic applications depended much on typology, Krogman's publications were generally more modern than Hooton's. In terms of parsimony, Hooton's works can be criticized in terms of his cumbersome typology, but not his ideas on arborealism and the adaptive radiation of the primates. Krogman's interest in roentgenographic cephalometry may have been motivated by a concern for parsimonious explanations of craniofacial growth. Indeed, research in the new physical anthropology can truly be said to stand on the shoulders of these two giants.     

The morphological and functional differentiation of the alimentary canal of the pig during ontogeny. II. Development and differentiation of the jejunum.

Morphological development and differentiation of the pig's jejunum during ontogenesis were studied. It was found that villi intestinalis are formed on about the 40th day of embryogenesis. The differentiation of absorptive epithelium, goblet cells and argentaffine cells as well as the formation of the Lieberkühn's crypts, and muscularis mucosae, occur by the end of the 2nd and at the beginning of the 3rd month of the prenatal development. The Paneth cells are found in the period around birth. After birth there is an adaptive rearrangement of the mucosa of jejunum affecting both the epithelium and the propria: the rearrangement is conditionally divided into two periods - from birth to the 3rd day, and from the 10th to the 20th day.     

Value and limits of serological methods: electrosyneresis and E.L.I.S.A. for the study of the prevalence of histoplasmosis in Mali

The authors have looked for circulating antibodies on 168 subjects for the study of the prevalence of histoplasmosis in Mali. Two serologic systems were employed: with counter-immunoelectrophoresis precipitating bands were detected in 42% of sera, while 57% were positive with Enzyme-linked immunosorbent assay. E.L.I.S.A. appear less specific because many cross-reactions were observed with other diseases.     

Heterotopic pancreas of the stomach. Histogenesis and immunohistochemistry.

Ordinary histological investigation has suggested that heterotopic pancreas of the stomach may have two types of histogenesis; one is development from immigrated fetal pancreas tissue, and the other is development from primitive gastric mucosal epithelium following penetration into the submucosa with subsequent erroneous differentiation into pancreas tissue. It is suspected that type-I lesions include the majority of cases caused by immigration from fetal pancreas, and that some type-II cases arise through erroneous differentiation of primitive gastric mucosal epithelium. With regard to immunohistochemical findings, cells positive for pancreatic polypeptide and amylase were much more numerous in the acini of type-I cases compared with type-II cases. Positive cells were found not infrequently in the acini of type-II cases after staining for pancreatic polypeptide, insulin, glucagon, somatostatin, serotonin, and gastrin. On the other hand, a small number of cells in islets were not infrequently positive for alpha 1-antitrypsin, alpha 1-antichymotrypsin, and amylase. It is considered that in the heterotopic pancreas, ductal cells have the potential to differentiate into acinar cells and islet cells, as is the cases in the orthotopic pancreas.