Gelation Dynamics upon Pressure-Induced Liquid-Liquid Phase Separation in a Water-Lysozyme Solution

Employing X-ray photon correlation spectroscopy, we measure the kinetics and dynamics of a pressure-induced liquid-liquid phase separation (LLPS) in a water-lysozyme solution. Scattering invariants and kinetic information provide evidence that the system reaches the phase boundary upon pressure-induced LLPS with no sign of arrest. The coarsening slows down with increasing quench depths. The g₂ functions display a two-step decay with a gradually increasing nonergodicity parameter typical for gelation. We observe fast superdiffusive (γ ≥ 3/2) and slow subdiffusive (γ < 0.6) motion associated with fast viscoelastic fluctuations of the network and a slow viscous coarsening process, respectively. The dynamics age linearly with time τ ∝ t_w, and we observe the onset of viscoelastic relaxation for deeper quenches. Our results suggest that the protein solution gels upon reaching the phase boundary.

Fetal microphthalmia diagnosed by magnetic resonance imaging

We report a case of fetal microphthalmia diagnosed midtrimester by ultrasound and fetal MRI. Included is a comparison of MRI measurements of normal fetuses at similar gestational age and a review of the literature.

Aminoglycoside ototoxicity in cystic fibrosis. Evaluation by high-frequency audiometry

In this study, we sought to determine the clinical usefulness of high-frequency audiometry (8000 to 20,000 Hz) in detecting aminoglycoside-induced increases in pure-tone hearing thresholds before they are noticed in conventionally tested frequencies. We measured hearing thresholds from 250 to 20,000 Hz in 22 patients with cystic fibrosis who were treated with aminoglycosides. The audiograms were age-matched and were compared with those from 13 patients with cystic fibrosis and 38 subjects without cystic fibrosis, all of whom had never received aminoglycoside therapy. In patients with cystic fibrosis who were treated with aminoglycosides (younger than 20 years), there were statistically significant elevations only in frequencies higher than 16,000 Hz. Patients with cystic fibrosis who were treated with aminoglycosides who were 20 years and older had elevated thresholds in all frequencies tested. Patients with cystic fibrosis who were not treated with aminoglycosides did not differ statistically from controls. High-frequency audiometry may serve as a useful measure of elevation in pure-tone hearing thresholds that precede noticeable loss of auditory acuity in patients with cystic fibrosis who are receiving long-term aminoglycoside therapy.

Hermansky-Pudlak syndrome: an immunologic assessment of 15 cases

PURPOSE

The Hermansky-Pudlak syndrome is an autosomal recessive disorder consisting of the triad of oculocutaneous albinism, a storage pool platelet defect, and multisystem tissue deposition of ceroid pigment. Although the underlying metabolic defect has not been identified, secondary or associated effects on the immune system are suggested by reports of an association with disorders such as pulmonary fibrosis, granulomatous colitis, lupus, and frequent bacterial infections. We evaluated a large group of patients with the Hermansky-Pudlak syndrome to assess immune competence in this condition.

PATIENTS AND METHODS

Fifteen patients with this syndrome were studied. Control subjects included healthy volunteers in the same age range as the patients. Peripheral blood lymphocytes and neutrophils were isolated according to previously described methods. Immunofluorescent staining, flow cytometry, and cytotoxicity assays were performed. Determination of lymphocyte transformation, mixed lymphocyte response, and neutrophil function was made.

RESULTS

Immunoglobulin levels, complement, lymphocyte subsets, natural killer and lymphokine-activated cytotoxicity, mixed lymphocyte responses, and lectin-induced transformation were normal in all patients. In addition, there was no evidence for a lymphocyte proliferative response to a preparation of urinary ceroid pigment isolated from these patients. Neutrophil function, including luminol-dependent chemiluminescence, chemotaxis, and aggregation was not significantly different from control values.

CONCLUSION

The results suggest that there is no generalized defect of peripheral blood lymphocyte or neutrophil function in the Hermansky-Pudlak syndrome. We propose that future studies should examine the possibility that associated disorders arise from a defect within the monocyte-macrophage system, perhaps secondary to ceroid accumulation.

Collaborative studies program on maternal and child health in New York State, 1981-83

With the passage of the Omnibus Reconciliation Act and the establishment of the block grant system in 1981, responsibility for the direction of many public health programs shifted from Federal to State government. This shift, coupled with funding cutbacks and the constraints of the current economic status of the country, has had an impact on the ability of the service delivery network to maintain service delivery programs. In the implementation of the Maternal and Child Health (MCH) Services Block Grant, collaboration among service, research, and training programs has been emphasized as an essential component to respond to the needs of service agencies and to provide relevant field experience for public health students. A program of projects centered on joint collaboration and support is described in this paper. Two of the 13 projects implemented over a 2-year period are highlighted. In 1981, the MCH Collaborative Studies Program was established, linking Columbia University School of Public Health, the New York State Health Department, and MCH service providers in New York City in an effort to identify underserved MCH populations, assess the impact of funding cutbacks, and define new strategies for service delivery programs. Graduate research assistants are assigned to participating agencies to coordinate the activities of each project.