Lung hypoplasia in congenital diaphragmatic hernia. A quantitative study of airway, artery, and alveolar development

From a case of congenital diaphragmatic hernia the pattern of growth of the airways, alveoli, and pulmonary arteries of both lungs, each hypoplastic, has been analysed quantitatively. The impairment of growth for each type of structure is not necessarily the same and differs in each lung. Airway and alveolar numbers are both greatly reduced, although the latter are more nearly normal when related to the number of terminal bronchioli in the lung. In each lung the size of the pulmonary artery at the hilum is appropriate to the lung volume but small for the age of the child. Muscle is found in much smaller arteries than is normal but not to a more peripheral level.

The way the lungs in a case of congenital diaphragmatic hernia might grow after surgical correction of the hernia is discussed and a plea made for respiratory physiological studies in such cases.

Growth of the alveoli and pulmonary arteries in childhood

Since alveolar and airway growth have previously been studied in greater detail than has arterial growth, the present study establishes the growth pattern of the arteries and relates this to that of the alveoli and airways.

The pattern of post-natal alveolar multiplication found is similar to that reported by Dunnill, but for all ages about 10% above his figure. Alveolar size hardly changes in the first three or four years of life but thereafter increases steadily. The complexity of alveolar shape increases from the age of 4 months.

In arteriograms the arterial lumen, both centrally and peripherally, increases 4- to 5-fold in the upper lobe, 3-fold in the lower. Microscopic examination shows a striking increase between 4 months and 3 years in the number of arteries below 200 μm. per unit area of lung tissue; after 5 years this number falls slightly, probably reflecting an increase in alveolar size.

Muscular, partially muscular and non-muscular arteries show a similar distribution over the same size range in the newborn as in the adult. During childhood, however, the arteries over this size range are free of muscle and much larger arteries show this mixed `population'. Between 11 and 19 years the adult pattern forms by progressive penetration of muscle into the acinus.

The thickness of the muscle coat of pulmonary artery branches falls to adult levels by the age of 4 months. Between birth and 5 years the medial area of arteries between 25 and 200 μm. in diameter per unit area of lung falls, but has risen again by 11 years.

Pulmonary arterial development during childhood: branching pattern and structure

In lungs from 18 children aged between birth and 11 years the development of the branching pattern and structure of the pulmonary arteries, particularly the intralobular and intra-acinar, has been quantitatively analysed after injection with a radio-opaque medium. Up to 18 months of age as new alveolar ducts appear conventional arterial branches develop within the acinus: supernumerary arteries increase in number up to 8 years as new alveoli form. Both types increase in size with age.

After birth there is an immediate drop in wall thickness of the vessels below 200 μm diameter while the larger vessels take up to 4 months to fall to adult thickness, suggesting two types of response—one dilatation, the other a growth rate change of the muscle cells. During childhood muscle cell formation in the intra-acinar arteries lags behind increase in artery size so that during childhood few muscular arteries are found within the acinus. The functional significance of these changes is discussed.

Vascular structure in lung tissue obtained at biopsy correlated with pulmonary hemodynamic findings after repair of congenital heart defects

At the time of surgical repair, a lung biopsy was performed on patients with congenital heart defects who either had pulmonary hypertension or in whom it would be likely to develop if the lesion were not corrected. Pulmonary vascular changes, assessed morphometrically and also according to the classification of Heath and Edwards (Circulation 18: 533, 1958), were correlated with the postoperative pulmonary hemodynamic findings: mean pulmonary arterial pressure the day after correction and mean pulmonary arterial pressure and pulmonary vascular resistance measured 1 year later. On the first postoperative day, increased mean pulmonary arterial pressure was uncommon in patients with morphometric grade A or B (mild) biopsy findings and Heath-Edwards grade N (normal), and if it was present it was of a mild degree. Mean pulmonary arterial pressure was commonly elevated in those with grade B (severe) or C (mild or severe) and Heath-Edwards grade I biopsy results and was more frequently elevated in those with grade II findings. Moderate-to-severe elevation of mean pulmonary arterial pressure was invariable in patients with Heath-Edwards grade III changes regardless of the morphometric grade. One year after repair, mean pulmonary arterial pressure and/or pulmonary vascular resistance were normal in all patients whose conditions were corrected surgically before 9 months of age regardless of the severity of the pulmonary vascular changes. Values were normal in patients whose conditions were repaired surgically at 9 months of age or later who had grade A or B (mild) morphometric findings with any Heath-Edwards grade or grade B (severe) morphometric findings with Heath-Edwards grade I but were increased in half of the patients with grade B (severe) morphometric findings and Heath-Edwards grade II or with grade C (mild or severe) and Heath-Edwards grade I or II changes. Pulmonary arterial pressure and pulmonary vascular resistance were increased in all patients whose conditions were repaired after 2 years of age with grade C morphometric findings and to a severe degree if associated with Heath-Edwards grade III. Thus, although the Heath-Edwards grade can usually be used to identify patients at risk for pulmonary hypertension in the early postoperative period, both the morphometric and the Heath-Edwards grades as well as the age of the patient at the time of repair can be used to determine whether pulmonary arterial pressure and resistance eventually return to normal or remain elevated.

Mode of regulation of natural killer cell activity by interferon

Whereas xenogeneic tumors such as baby hamster kidney or HeLa cells grow in nude mice, the same cells persistently infected with a variety of viruses are rejected. Spleen cells from normal nude mice were found to be induced to produce interferon and to exert natural killer (NK) activity on virus persistently infected (PI) tumor cells, and not on uninfected parental cells in vitro. The phenotype of the interferon-producing cells and the NK effector cells was found to be the same namely, Qa 5(+), Ly 5(+), ganglio-N- tetraosylceramide, with 35 percent of the NK cells also expressing Thy 1.2. NK activity against virus PI tumor cell lines could be nonspecifically augmented both in vivo and in vitro by prior contact with virus PI tumor cells. It was unambiguously demonstrated with chemically homogeneous mouse interferon that interferon, and not a contaminant, was responsible for the augmentation of NK activity in vitro. Studies on the mode of interferon action in augmenting NK activity revealed that the target cell for interferon action was serologically distinct from the NK effector cell. Anti-Ly 5 + complement (C)-treated spleen cells were depleted of NK activity and the ability to produce interferon, but, upon incubation with interferon for 1-3 h, regained both NK activity and susceptibility to anti-Ly 5 + C. Treatment with anti-Qa 5 + C eliminated NK activity, which could not be restored by the addition of interferon. We conclude that interferon produced by Ly 5(+) cells in response to virus PI tumor cells acts on Ly 5(-) precursor cells and induces their differentiation into functional Ly 5(+) NK effector cells.

Rat pulmonary circulation after chronic hypoxia: hemodynamic and structural features

In 55 Sprague-Dawley rats (mean wt, 277 +/- 6.2 g) exposed to hypobaric hypoxia (air at 380 mmHg), and 23 weight-matched controls kept in room air, pulmonary and systemic artery pressures were measured daily for 2 wk via indwelling catheters. After each day of exposure, 1 or 2 hypoxic rats, to a total of 20, and 5 control rats were killed during the experiment. In these rats, the pulmonary arterial tree was injected post mortem with barium-gelatin and inflated with formaldehyde solution, and three structural features were quantified microscopically: 1) abnormal extension of muscle into peripheral arteries where it is not normally present (EMPA); 2) increased wall thickness of the normally muscular arteries, expressed as a percentage of external diameter (%WT); and 3) reduction in artery number expressed as an increase in the ratio of alveoli to arteries (A/a). Mean pulmonary artery pressure (Ppa) rose significantly after day 3 of hypoxic exposure (P less than 0.05) and had doubled by day 14; the mean systemic artery pressure (Psa) of hypoxic rats and Ppa and Psa of control rats were unchanged. The level of Ppa correlated with the degree of structural changes; for EMPA, r = 0.84; for %WT, r = 0.64; and for A/a, r = 0.73 (P less than 0.001 in all.

High resolution mapping of genetic factors affecting abdominal bristle number in Drosophila melanogaster

Factors responsible for selection response for abdominal bristle number and correlated responses in sternopleural bristle number were mapped to the X and third chromosome of Drosophila melanogaster. Lines divergent for high and low abdominal bristle number were created by 25 generations of artificial selection from a large base population, with an intensity of 25 individuals of each sex selected from 100 individuals of each sex scored per generation. Isogenic chromosome substitution lines in which the high (H) X or third chromosome were placed in an isogenic low (L) background were derived from the selection lines and from the 93 recombinant isogenic (RI) HL X and 67 RI chromosome 3 lines constructed from them. Highly polymorphic neutral roo transposable elements were hybridized in situ to the polytene chromosomes of the RI lines to create a set of cytogenetic markers. These techniques yielded a dense map with an average spacing of 4 cM between informative markers. Factors affecting bristle number, and relative viability of the chromosome 3 RI lines, were mapped using a multiple regression interval mapping approach, conditioning on all markers > or = 10 cM from the tested interval. Two factors with large effects on abdominal bristle number were mapped on the X chromosome and five factors on the third chromosome. One factor with a large effect on sternopleural bristle number was mapped to the X and two were mapped to the third chromosome; all factors with sternopleural effects corresponded to those with effects on abdominal bristle number. Two of the chromosome 3 factors with large effects on abdominal bristle number were also associated with reduced viability. Significant sex-specific effects and epistatic interactions between mapped factors of the same order of magnitude as the additive effects were observed. All factors mapped to the approximate positions of likely candidate loci (ASC, bb, emc, h, mab, Dl and E(spl), previously characterized by mutations with large effects on bristle number.

On the heterogeneity of murine natural killer cells

The heterogeneity of cells capable exerting spontaneous cytotoxicity in vitro was explored using antisera to several genetically determined surface markers on mouse lymphocytes. Four phenotypes of cells derived either from fresh or cultured murine lymphoid tissue were found to exert natural killer (NK) activity in vitro. One affector cell subset, termed NKI cells, had the serological phenotype of Thy-1-, Lyt-2-, Qa5+, and lysed measles virus persistently infected target cells (HeLa-Ms) but not P815 mastocytoma cells. It corresponds with the NK cells described in most systems in which lymphoma targets are commonly used. A second subset, with the same target cell specificity, termed NKT is a thymus-independent cell with the phenotype Thy-1+, Lyt-2-, Qa-5+, Ly-5+. A third subset of NK cells, termed T killer (TK) cells deriving from cultures of conventional but not nude mouse spleens, mediated spontaneous cytotoxicity of P815 mastocytoma cells, but not of virus-infected targets. It has a phenotype of Thy-1+, Lyt-2+, Qa-5-, Ly-5+, apparently identical with that of conventional, antigen-specific cytotoxic T lymphocytes. The fourth phenotype of NK cells, termed NKM, derived primarily from cultures of bone marrow, is cytotoxic for HeLa-measles but not P815, and expresses only Ly-5+ among the various markers tested. Beige mice possess normal TK and NKM activities, but had normal NKI, NKT as well as NKM activity. All NK cell subsets express the Ly-5 surface marker. The existence of four phenotypically distinct NK effector cells was strengthened by studies on selective regulation of their activity by two different biological factors. Interferon (IFN) augmented NK activity of primarily one of the subsets examined, the NKI cell; the activity of IFN on NKT cells could not be directly tested, but IFN was without positive effect on TK or NKM cells. In contrast, partially purified IFN-free interleuken 2 (IL-2) augmented the activities of both the TK and NKT subsets, but not of NKI or NKM cell. IL-2 was active in augmenting NK activity in spleen cells obtained from both conventional and nu/nu mice, but was without effect on spleens of nu/nu mice depleted of Thy-1+ cells. These and other data suggest that IL-2 acts primarily, if not exclusively, on THy-1+ cells. These results strengthen the view that natural cytotoxicity in vitro can be mediated by several distinct cell populations under different genetic and regulatory control and indicate the importance of defining and delineating the cell lineages of each and the role of the independent subsets in resistance to virus infections and tumors in vivo.

The lungs in congenital bilateral renal agenesis and dysplasia

A detailed quantitative analysis was made of the lungs from 8 infants dying with bilateral renal agenesis or dysplasia. Total lung volume was reduced in all cases, particularly in those with renal agenesis. In both groups there was a reduction in number of airway generations, indicating interference with development at between 12 and 16 weeks' gestation. The alveoli in each acinus were reduced in size and, in some cases, number--although their stage of differentiation was normal for age--pointing to a disturbance of growth during later fetal life also. As liquor is largely non-renal in origin at least up to 16 weeks' gestation, it seems that there are factors other than the oligohydramnios interfering in early lung growth in these cases, such as reduced proline production by the kidney.

Effect of scoliosis on growth of alveoli and pulmonary arteries and on right ventricle

During childhood the lung not only grows in size but alveoli and arteries multiply and the pattern of muscularity of the arteries changes. A quantitative study is here reported on 4 cases of scoliosis. The limitation and distortion of space available affect lung growth. In scoliosis, alveoli are too few in number, often emphysematous, and may even atrophy, the changes being irregularly distributed throughout a lobe or lung. Generally, the size of the large pulmonary arteries is appropriate to the lobar volume and hence small for the age of the child: arterial muscle hypertrophy and abnormal extension to the periphery were seen only in 2 of the 4 cases in which there was right ventricular hypertrophy. In these, hypoxaemia had been present for some time before death and this, not hypoplasia, seemed responsible for the muscle hypertrophy. In 2 cases where scoliosis was associated with a mesodermal dysplasia, there was an excessive number of intra-acinar arteries.

New pathological findings in emphysema of childhood. 1. Polyalveolar lobe with emphysema

A new pathological entity is here described—a polyalveolar lobe with or without emphysema—giving rise to the clinical features of childhood lobar emphysema.

A detailed and quantitative study of the airways, alveoli and arteries was carried out on the left upper lobe removed because of shortness of breath, thought to be due to `childhood lobar emphysema'. The child was 17 days old and the radiograph showed hypertransradiancy of the left lung. The alveolar number was increased five-fold. Alveolar size was normal, so it was found that emphysema, accepted today as a structural diagnosis, was not present. The increase in alveolar number seemed confined to the apical, posterior, and anterior segments, the lingula being unaffected. By contrast, the airways and arteries were normal for age in number, size and structure, suggesting that the condition was a `giantism' of the alveolar region. The blood flow was probably too low for the lobar volume; certainly the excessive alveolar number could not be due to increase in blood flow.

In two further specimens, previously dissected, a similar polyalveolar condition was found, associated with emphysema. The patients were older at the time of surgical resection and the emphysema may have developed post-natally. In all three cases the radiographic features had suggested emphysema. It is suggested that the condition be called `polyalveolar lobe', `with emphysema' or `without emphysema' being added as a separate item to the description.

Persistent fetal circulation: Newly recognized structural features

Three infants died with pulmonary hypertension of unknown cause during the first three months of life. Their lungs were examined using quantitative morphologic techniques. In all three cases the intra-acinar pulmonary arteries were more muscular than normal, as shown both by an increase in thickness of the muscle coat in arteries which are normally muscular, and by extension of muscle into smaller and more peripheral intra-acinar arteries not normally muscular at this age. It is suggested that "persistent pulmonary hypertension" of the newborn infant is, in some infants, due to a structural abnormality of the pulmonary circulation which is present at birth.

A reconstruction of the duct system and secretory tubules of the human bronchial submucosal gland

A graphic reconstruction has been made of a submucosal gland from a normal human main bronchus, revealing a collecting duct not previously described. Ciliated respiratory epithelium dips into the gland opening to line the first part of the duct, the ciliated duct, and then gives way, in the collecting duct, to an epithelium composed of tall, columnar, eosinophilic cells containing numerous large mitochondria. This cell structure suggests that the collecting duct controls ionic and water concentration. From the collecting duct arise secretory tubules lined by mucous cells—mucous tubules. Tubules lined by serous cells—serous tubules—arise from mucous tubules either terminally or laterally.

Persistent hypoplasia of the lung after repair of congenital diaphragmatic hernia

Quantitative analysis has been used to assess growth in a lung from an infant aged 21/2 months in whom a diaphragmatic hernia was repaired at birth. The lungs had been abnormally small at birth but at 21/2 months were of normal volume. Alveoli had multiplied at the normal rate after birth but had not reached the number normal of age. The number per acinus was normal but the alveoli were increased in size, particularly in the left lung. The airway number, and thus alveolar, acinar, and arterial number, were all reduced in both lungs, the ipsilateral being most affected. The pulmonary blood vessels in both lungs showed an increased muscularity that did not correlate with lung volume or alveolar number, a feature that may have been present at birth. The degrees of hypoplasia in the two lungs were different at birth and this difference had been maintained. The effect of the disturbance to lung growth on the functioning of the lung is discussed.

Compression of intrapulmonary bronchi by abnormally branching pulmonary arteries associated with absent pulmonary valves

In 3 patients with absent pulmonary valve syndrome and absent ductus arteriosus, the lungs were injected and analyzed postmortem using morphometric techniques. Two patients had tetralogy of Fallot and 1 had D-transposition of the great arteries, the latter being the first autopsy-proved case of absent pulmonary valve with transposition. In addition to the expected dilatation of the central pulmonary arteries and compression of the mainstem bronchi, postmortem pulmonary arteriography revealed a bizarre pattern of hilar branching. Instead of single segmental arteries, tufts of arteries arose which entwined and compressed the intrapulmonary bronchi. In all 3 patients the histologic structure of the pulmonary arteries was abnormal. The elastic lamina of the media of the right and left pulmonary arteries were increased in number outside the lung, but were decreased within the lung. At both sites, the elastic laminae were thickened and fragmented. In the 2 ventilator-dependent patients, there was slight medial hypertrophy and extension of muscle into normally nonmuscular arteries. In 1 of the 2 cases in which the number of bronchial generations was counted, they were decreased, and in the 1 case in which bronchial count was unknown, alveolar multiplication was severely impaired. Therefore, our data may explain why, in some patients with absent pulmonary valve syndrome, relief of compression of the mainstem bronchi alone does not appreciably alleviate or reverse severe respiratory disease.

An organ culture study of the effect of drugs on the secretory activity of the human bronchial submucosal gland

1. The incorporation of tritiated glucose into bronchial gland cells enables their glycoprotein secretion to be followed by radioautography. The number of cells from which secretion is observed after 4 h of cell culture is the secretory index.

2. Large variations in secretory index were observed between the bronchi of different subjects, but the secretory index was proportional to gland size.

3. The secretory index was increased by parasympathomimetic drugs and diminished by parasympatholytic drugs, the magnitude of the effect being proportional to gland size in the former and inversely proportional in the latter case.

4. Sympathomimetic drugs, bradykinin and mucolytic drugs had no effect on the secretory index.

5. In cystic fibrosis, bronchitis and bronchiectasis gland size and not the disease process was the main determinant of the secretory index.

Age and sex influence on pulmonary hypertension of chronic hypoxia and on recovery

To study the influence of age and sex on the hemodynamic and structural response of the pulmonary vascular bed to chronic hypobaric hypoxia, "infant" Sprague-Dawley rats from 8 days old and "adult" rats from 9 wk old, each group including both sexes, were exposed to half atmospheric pressure for 1 mo and then allowed to recover in room air for up to 3 mo. During hypoxic exposure, pulmonary artery hypertension (Ppa) developed in all groups. The level of Ppa was similar in both male and female infant and in male adult rats but was significantly lower (P < 0.01) in the female adult rats. After recovery in room air, only partial regression of Ppa had occurred in all groups (P < 0.001). In male and female adult rats, recovery values were similar but infant rats had more residual Ppa than adults (P < 0.001). The structural changes that developed during hypoxia, especially the abnormal presence of muscle in small and peripheral intra-acinar arteries, were more severe in male adult rats compared with female adults (P < 0.01) and in infants of both sexes compared with male adults (P < 0.01). After recovery, residual structural changes were present in all rat groups but were most severe in the infants (P < 0.01).

cAMP delays disappearance of gap junctions between pairs of rat hepatocytes in primary culture

Pages C1–C11: J. A. Sáez, W. A. Gregory, T. Watanabe, R. Dermietzel, E. L. Hertzberg, L. Reid, M. V. L. Bennett, and D. C. Spray. “cAMP delays disappearance of gap junctions between pairs of rat hepatocytes in primary culture.” Page C8: Fig. 8B should appear as follows:

Goblet cell increase in rat bronchial epithelium after exposure to cigarette and cigar tobacco smoke

Both cigar and cigarette tobacco produce an increase in the number of goblet cells in the rat trachea and intrapulmonary airways over a six-week period. The increase in goblet cells is similar for the two types of tobacco; in both it is proportional to increase in dose and greatest in the proximal intrapulmonary airways.