Sonic phase delay from trachea to chest wall: spatial and inhaled gas dependency

A parametric phase delay estimation technique is used to determine the spatial and inhaled gas composition dependencies of sound propagation time through an intact human lung at frequencies of 150–1200 Hz. Noise transmission measurements from the mouth to the extrathoracic trachea and six sites on the posterior chest wall are performed in 11 healthy adult subjects at resting lung volume after equilibration with air, an 80% helium-20% oxygen mixture, and an 80% sulfurhexafluoride-20% oxygen mixture. The phase delay, τ(f), exhibits a bilateral asymmetry with relatively decreased delays to the left posterior chest as compared with the right. The phase delay to lower lung sites is greater than to upper sites at frequencies below 300 Hz; yet the opposite is found at higher frequencies, indicating changing propagation pathways with frequency. There is no measurable effect of inhaled gas composition on τ(f) below 300 Hz. At higher frequencies, changes in τ(f) that reflect the relative sound speed of the particular inhaled gas are observed. These findings support and extend previous measurements and hypotheses concerning the strong frequency dependence of the acoustical properties of the intact respiratory system.     

Primary structure of myosin from the striated adductor muscle of the Atlantic scallop, Pecten maximus, and expression of the Regulatory Domain

We have determined the complete cDNA and deduced amino acid sequences of the heavy chain, regulatory light chain and essential light chain which constitute the molecular structure of myosin from the striated adductor muscle of the scallop, Pecten maximus. The deduced amino acid sequences of P. maximus regulatory light chain, essential light chain and heavy chain comprise 156, 156 and 1940 amino acids, respectively. These myosin peptide sequences, obtained from the most common of the eastern Atlantic scallops, are compared with those from three other molluscan myosins: the striated adductor muscles of Argopecten irradians and Placopecten magellanicus, and myosin from the siphon retractor muscle of the squid, Loligo pealei. The Pecten heavy chain sequence resembles those of the other two scallop sequences to a much greater extent as compared with the squid sequence, amino acid identities being 97.5% (A. irradians), 95.6% (P. magellanicus) and 73.6% (L. pealei), respectively. Myosin heavy chain residues that are known to be important for regulation are conserved in Pecten maximus. Using these Pecten sequences, we have overexpressed the regulatory light chain, and a combination of essential light chain and myosin heavy chain fragment, separately, in E. coli BL21 (DE3) prior to recombination, thereby producing Pecten regulatory domains without recourse to proteolytic digestion. The expressed regulatory domain was shown to undergo a calcium-dependent increase (7%) in intrinsic tryptophan fluorescence with a mid-point at a pCa of 6.6.     

Lipoblastoma and lipoblastomatosis in infancy and childhood: histopathologic, ultrastructural, and cytogenetic features

Lipoblastoma is a relatively rare tumor that occurs in infancy and early childhood and arises from embryonic white fat. Although a benign tumor, lipoblastomas tend to recur and may resemble myxoid liposarcoma. The authors report 26 cases over a 15-year period at Texas Children's Hospital. There was a slight female predilection (14F:12M). The most common symptom was a painless mass with or without increasing size. The trunk, extremities, head and neck, retroperitoneum, inguinal canal, peritoneal cavity, and lung were the tumor sites. Most tumors were circumscribed lipoblastomas and the minority were diffuse infiltrative lipoblastomatosis. Reexcision for residual or recurrent tumor was necessary more frequently in patients with lipoblastomatosis. Histopathologic examination and ultrastructural examination revealed cellular neoplasms composed of immature adipocytes with relatively well-defined septa, frequent lipoblasts, a fine vascular network, and often a myxoid appearance resembling myxoid liposarcoma. Cytogenetics was performed in 4 cases with chromosome 8q abnormality being most common. The major concern with lipoblastoma in children is to completely excise the tumor to avoid leaving residual tumor and to prevent recurrences. Confusion with myxoid liposarcoma, well-differentiated liposarcoma, and typical lipomas may occur. Although asymptomatic, lipoblastomas may cause dysfunction of other organ systems due to mass effect. Complete surgical excision with at least 2 years of follow-up is the preferred therapy.     

Nuclear and cytoplasmic bcl-2 expression in endometrial hyperplasia and adenocarcinoma

The bcl-2 proto-oncogene, which inhibits programmed cell death (apoptosis), has recently been found to be cyclically expressed in human endometrium. In order to investigate its role in endometrial hyperlasia and neoplasia, bcl-2 expression was studied in 25 cases of endometrial carcinoma and 20 cases of endometrial hyperplasia (eight simple, two complex, and ten atypical hyperplasias). Uniform intense cytoplasmic bcl-2 expression was found in all cases of non-atypical hyperplasia, and less strong positivity in eight out of ten cases of atypical hyperplasia. In well-differentiated carcinomas, nine out of ten showed weak to moderate bcl-2 expression, whereas six out of seven poorly differentiated carcinomas were bcl-2-negative. Moderately differentiated tumours were an intermediate group, with six out of eight being positive. Widespread localization of bcl-2 protein to the chromosomes of dividing cells was also demonstrated, regardless of cytoplasmic bcl-2 expression, with rare staining of interphase nuclei. Our findings suggest a role for bcl-2 in the natural history of endometrial neoplasia and studies are needed to determine its usefulness as a prognostic marker. The finding of bcl-2 localization to chromosomes has important implications for its mode and site of action.     

Studies on carboxymethylcellulose: Conductivity measurements of solutions, 2

The conductivity behaviour of carboxymethylcellulose (CMC) solutions was studied using different types of neutralizing reagents (LiOH, NaOH, KOH); the following order of conductance of CMC solutions was observed: Li⁺ < Na⁺ < K⁺. This conductance behaviour of CMC solutions with respect to the size of counterions is explained qualitatively as well as quantitatively. Binding of Li⁺, Na⁺ and K⁺ ions onto the polymer molecule and the influence of the degree of substitution, ,DS , on the conductivity of CMC were also investigated. The conductivity of CMC solutions as well as the fraction of bound counterions increase with increasing DS , at a given degree of neutralization (α) for each type of counterion. The effect of DS on the polymer charge fraction, i/s, is in line with the counterion condensation phenomena of Oosawa. The results regarding the dependence of the equivalent conductance of the polyion, Δ_p, on DS are compared with literature data.     

Early experience in using and 18 Me V linear accelerator for mycosis fungoides at Howard University Hospital.

This paper describes the problems and solutions in using 18 MeV linear accelerator, with minimum 6 MeV electron capability, for total skin irradiation for mycosis fungoides. The 6 MeV electron energy can be degraded to acceptable electron energy of 3.2 MeV by interposing a plexiglass sheet of 9.6 mm in the beam. To minimize the bremsstrahlung, the degrading plexiglass should be kept away from the machine head. A wide area with uniform dose distribution over single plane can be achieved by using dual fields but homogenous dose distribution over irregular body surface cannot be achieved mainly because of self-shielding. The nails and the ocular lens can be easily shielded from the low energy electrons with 1.5 mm lead shield.     

Identification of two mutations in a compound heterozygous child with dihydrolipoamide dehydrogenase deficiency

An infant girl with elevated blood lactate, pyruvate, and plasma branched-chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3; dihydrolipoamide: NAD+ oxidoreductase, EC 1.8.1.4) deficiency. Activities of the pyruvate dehydrogenase complex and E3 from patient were 26 and 2% of controls in blood lymphocytes, and 11 and 14% in cultured skin fibroblasts, respectively. Western blot analysis demonstrated that the amount of E3 protein in fibroblasts from the patient and her father was about half of controls, while Northern blot analysis showed normal amounts of E3 RNA. DNA sequencing of cloned full-length E3 cDNAs from the patient revealed two mutations in separate alleles. One is a single base insertion of an extra adenine in the last codon of the leader peptide sequence (TAC-->TAAC) leading to a nonsense mutation which results in the premature termination of the precursor E3 polypeptide (Y35X). The other is a missense mutation due to substitution of guanine for adenine, causing an Arg-->Gly substitution at amino acid 460 of the mature protein (R460G) which triggers the loss of E3 activity probably by structural change in the E3 dimer. DNA sequencing of E3 cDNAs from the parents demonstrated that the nonsense mutation was inherited from the father and the missense mutation was inherited from the mother.