Deferoxamine Prevents Neonatal Posthemorrhagic Hydrocephalus Through Choroid Plexus-Mediated Iron Clearance

Posthemorrhagic hydrocephalus occurs in up to 30% of infants with high-grade intraventricular hemorrhage and is associated with the worst neurocognitive outcomes in preterm infants. The mechanisms of posthemorrhagic hydrocephalus after intraventricular hemorrhage are unknown; however, CSF levels of iron metabolic pathway proteins including hemoglobin have been implicated in its pathogenesis. Here, we develop an animal model of intraventricular hemorrhage using intraventricular injection of hemoglobin at post-natal day 4 that results in acute and chronic hydrocephalus, pathologic choroid plexus iron accumulation, and subsequent choroid plexus injury at post-natal days 5, 7, and 15. This model also results in increased expression of aquaporin-1, Na+/K+/Cl- cotransporter 1, and Na+/K+/ATPase on the apical surface of the choroid plexus 24 h post-intraventricular hemorrhage. We use this model to evaluate a clinically relevant treatment strategy for the prevention of neurological sequelae after intraventricular hemorrhage using intraventricular administration of the iron chelator deferoxamine at the time of hemorrhage. Deferoxamine treatment prevented posthemorrhagic hydrocephalus for up to 11 days after intraventricular hemorrhage and prevented the development of sensorimotor gating deficits. In addition, deferoxamine treatment facilitated acute iron clearance through the choroid plexus and subsequently reduced choroid plexus iron levels at 24 h with reversal of hemoglobin-induced aquaporin-1 upregulation on the apical surface of the choroid plexus. Intraventricular administration of deferoxamine at the time of intraventricular hemorrhage may be a clinically relevant treatment strategy for preventing posthemorrhagic hydrocephalus and likely acts through promoting iron clearance through the choroid plexus to prevent hemoglobin-induced injury.

Gold nanoparticle-enhanced X-ray microtomography of the rodent reveals region-specific cerebrospinal fluid circulation in the brain

Cerebrospinal fluid (CSF) is essential for the development and function of the central nervous system (CNS). However, the brain and its interstitium have largely been thought of as a single entity through which CSF circulates, and it is not known whether specific cell populations within the CNS preferentially interact with the CSF. Here, we develop a technique for CSF tracking, gold nanoparticle-enhanced X-ray microtomography, to achieve micrometer-scale resolution visualization of CSF circulation patterns during development. Using this method and subsequent histological analysis in rodents, we identify previously uncharacterized CSF pathways from the subarachnoid space (particularly the basal cisterns) that mediate CSF-parenchymal interactions involving 24 functional-anatomic cell groupings in the brain and spinal cord. CSF distribution to these areas is largely restricted to early development and is altered in posthemorrhagic hydrocephalus. Our study also presents particle size-dependent CSF circulation patterns through the CNS including interaction between neurons and small CSF tracers, but not large CSF tracers. These findings have implications for understanding the biological basis of normal brain development and the pathogenesis of a broad range of disease states, including hydrocephalus.

Modeling Neonatal Intraventricular Hemorrhage through Intraventricular Injection of Hemoglobin

Neonatal intraventricular hemorrhage (IVH) is a common consequence of premature birth and leads to brain injury, posthemorrhagic hydrocephalus (PHH), and lifelong neurological deficits. While PHH can be treated by temporary and permanent cerebrospinal fluid (CSF) diversion procedures (ventricular reservoir and ventriculoperitoneal shunt, respectively), there are no pharmacological strategies to prevent or treat IVH-induced brain injury and hydrocephalus. Animal models are needed to better understand the pathophysiology of IVH and test pharmacological treatments. While there are existing models of neonatal IVH, those that reliably result in hydrocephalus are often limited by the necessity for large-volume injections, which may complicate modeling of the pathology or introduce variability in the clinical phenotype observed. Recent clinical studies have implicated hemoglobin and ferritin in causing ventricular enlargement after IVH. Here, we develop a straightforward animal model that mimics the clinical phenotype of PHH utilizing small-volume intraventricular injections of the blood breakdown product hemoglobin. In addition to reliably inducing ventricular enlargement and hydrocephalus, this model results in white matter injury, inflammation, and immune cell infiltration in periventricular and white matter regions. This paper describes this clinically relevant, simple method for modeling IVH-PHH in neonatal rats using intraventricular injection and presents methods for quantifying ventricle size post injection.

Etiology- and region-specific characteristics of transependymal cerebrospinal fluid flow

OBJECTIVE

Transependymal flow (TEF) of CSF, often delineated as T2-weighted hyperintensity adjacent to the lateral ventricles on MRI, is a known imaging finding, usually in the setting of CSF flow disturbances. Specific radiological features of TEF and their relationships with clinical markers of hydrocephalus and underlying disease pathology are not known. Here, the authors describe the radiological features and clinical associations of TEF with implications for CSF circulation in the setting of intracranial pathology.

METHODS

After obtaining IRB review and approval, the authors reviewed the radiological records of all patients who underwent intracranial imaging with CT or MRI at St. Louis Children's Hospital, St. Louis, Missouri, between 2008 and 2019 to identify individuals with TEF. Then, under direct review of imaging, TEF pattern, degree, and location and underlying pathology and other radiological and clinical features pertaining to CSF circulation and CSF disturbances were noted.

RESULTS

TEF of CSF was identified in 219 patients and was most prevalent in the setting of neoplasms (72%). In 69% of the overall cohort, TEF was seen adjacent to the anterior aspect of the frontal horns and the posterior aspect of the occipital horns of the lateral ventricles, and nearly half of these patients also had TEF dorsal to the third ventricle near the splenium of the corpus callosum. This pattern was independently associated with posterior fossa medulloblastoma when compared with pilocytic astrocytoma (OR 4.75, 95% CI 1.43-18.53, p = 0.0157). Patients with congenital or neonatal-onset hydrocephalus accounted for 13% of patients and were more likely to have TEF circumferentially around the ventricles without the fronto-occipital distribution. Patients who ultimately required permanent CSF diversion surgery were more likely to have the circumferential TEF pattern, a smaller degree of TEF, and a lack of papilledema at the time of CSF diversion surgery.

CONCLUSIONS

CSF transmigration across the ependyma is usually restricted to specific periventricular regions and is etiology specific. Certain radiological TEF characteristics are associated with tumor pathology and may reflect impaired or preserved ependymal fluid handling and global CSF circulation. These findings have implications for TEF as a disease-specific marker and in understanding CSF handling within the brain.

[A novel nomogram for individualized preoperative prediction of lymph node metastasis in patients with intrahepatic cholangiocarcinoma]

Objective: Constructing and validating a nomogram model for preoperative prediction of intrahepatic cholangiocarcinoma (ICC) lymph node metastasis to assist decision making during surgery. Methods: Retrospectively collecting the clinical and pathological data of 1 031 ICC patients who underwent partial hepatectomy at Eastern Hepatobiliary Surgery Hospital of Naval Military Medical University,General Hospital of Eastern Theater Command,or Zhongda Hospital Southeast University from January 2003 to January 2014. There were 682 males and 349 females; mean age was 54.7 years(range:18 to 82 years). There were 562 patients who underwent lymph node dissection and 469 patients who did not. Among the patients in the dissection group,Lasso regression method was used to filtrate preoperative variables related to lymph node metastasis and establish a nomogram. Bootstrap method was used to internally validate the discrimination of the nomogram,and the accuracy of the nomogram was assessed by using calibration curves. Patients were divided into low-moderate and high-risk groups based on model prediction probability. Propensity score matching(PSM) was used to analyze the overall survival (OS) and recurrence-free survival (RFS) of patients with and without lymph node dissection in the two groups,and to judge the importance of lymph node dissection in the two groups. Results: Six factors related to ICC lymph node metastasis were determined by Lasso regression,including hepatitis B surface antigen,CA19-9,age,lymphadenopathy,carcinoembryo antigen and maximum tumor diameter. These factors were integrated into a nomogram to predict ICC lymph node metastasis. The aera under curve value was 0.764,and the C-index was 0.754. Stratified analysis showed that OS and RFS in the high-risk group of lymph node metastasis were significantly lower than those in the low-medium risk group(median OS:14.6 months vs. 27.0 months,P<0.01; median RFS:9.1 months vs. 15.5 months,P<0.01). In the high-risk group,the median OS was 16.7 months and 6.3 months(Log-rank test: P=0.187;Wilcoxon test:P=0.046),and the median RFS was 11.0 months and 4.8 months(P=0.403),respectively in the lymph node dissection group and undissected group after PSM. In the low-medium-risk group,the median OS was 22.7 months and 26.7 months(P=0.288),and the median RFS was 13.0 months and 14.5 months(P=0.306),respectively in the lymph node dissection group and undissected group after PSM. Conclusions: The nomogram could be used for preoperative prediction of lymph node metastasis and prognostic stratification in patients with ICC. For patients with high risk of lymph node metastasis predicted by the model,active dissection should be performed. For patients predicted to be at low-moderate risk,lymph node dissection might be optional in some specific cases.

Single-center cost comparison analysis of stereoelectroencephalography with subdural grid and strip implantation

OBJECTIVE

Use of invasive stereoelectroencephalography (SEEG) has gained traction recently. However, scant research has investigated the costs and resource utilization of SEEG compared with subdural grid (SDG)-based techniques in pediatric patients. Here, the authors have presented a retrospective analysis of charges associated with SEEG and SDG monitoring at a single institution.

METHODS

The authors performed a retrospective case series analysis of pediatric patients with similar characteristics in terms of age, sex, seizure etiology, and epilepsy treatment strategy who underwent SEEG or SDG monitoring and subsequent craniotomy for resection of epileptogenic focus at St. Louis Children Hospital, St. Louis, Missouri, between 2013 and 2020. Financial data, including hospital charges, supplies, and professional fees (i.e., those related to anesthesia, neurology, neurosurgery, and critical care), were adjusted for inflation to 2020 US dollars.

RESULTS

The authors identified 18 patients (9 underwent SEEG and 9 underwent SDG) with similar characteristics in terms of age (mean [range] 13.6 [1.9-21.8] years for SDG patients vs 11.9 [2.4-19.6] years for SEEG patients, p = 0.607), sex (4 females underwent SDG vs 6 females underwent SEEG, p = 0.637), and presence of lesion (5 patients with a lesion underwent SDG vs 8 underwent SEEG, p = 0.294). All patients underwent subsequent craniotomy for resection of epileptogenic focus. SEEG patients were more likely to have a history of status epilepticus (p = 0.029). Across 1 hospitalization for each SDG patient and 2 hospitalizations for each SEEG patient, SEEG patients had a significantly shorter mean operating room time (288 vs 356 minutes, p = 0.015), mean length of stay in the ICU (1.0 vs 2.1 days, p < 0.001), and tended to have a shorter overall length of stay in the hospital (8.4 vs 10.6 days, p = 0.086). Both groups underwent invasive monitoring for similar lengths of time (5.2 days for SEEG patients vs 6.4 days for SDG patients, p = 0.257). Time to treatment from the initial invasive monitoring evaluation was significantly longer in SEEG patients (64.6 vs 6.4 days, p < 0.001). Neither group underwent readmission within the first 30 days after hospital discharge. Seizure outcomes and complication rates were similar. After adjustment for inflation, the average total perioperative charges were $104,442 for SDG and $106,291 for SEEG (p = 0.800).

CONCLUSIONS

Even though 2 hospitalizations were required for SEEG and 1 hospitalization was required for SDG monitoring, patients who underwent SEEG had a significantly shorter average length of stay in the ICU and operating room time. Surgical morbidity and outcomes were similar. Total perioperative charges for invasive monitoring and resection were approximately 2% higher for SEEG patients when corrected for inflation, but this difference was not statistically significant.

Multivariate analysis of associations between clinical sequencing and outcome in glioblastoma

BACKGROUND

Many factors impact survival in patients with glioblastoma, including age, Karnofsky Performance Status, postoperative chemoradiation, IDH1/2 mutation status, MGMT promoter methylation status, and extent of resection. High-throughput next-generation sequencing is a widely available diagnostic tool, but the independent impact of tumors harboring specific mutant genes on survival and the efficacy of extent of resection are not clear.

METHODS

We utilized a widely available diagnostic platform (FoundationOne CDx) to perform high-throughput next-generation sequencing on 185 patients with newly diagnosed glioblastoma in our tertiary care center. We performed multivariate analysis to control for clinical parameters with known impact on survival to elucidate the independent prognostic value of prevalent mutant genes and the independent impact of gross total resection.

RESULTS

When controlling for factors with known prognostic significance including IDH1/2 mutation and after multiple comparisons analysis, CDKN2B and EGFR mutations were associated with reduced overall survival while PTEN mutation was associated with improved overall survival. Gross total resection, compared to other extent of resection, was associated with improved overall survival in patients with tumors harboring mutations in CDKN2A, CDKN2B, EGFR, PTEN, TERT promoter, and TP53. All patients possessed at least one of these 6 mutant genes.

CONCLUSIONS

This study verifies the independent prognostic value of several mutant genes in glioblastoma. Six commonly found mutant genes were associated with improved survival when gross total resection was achieved. Thus, even when accounting for known predictors of survival and multiple mutant gene comparisons, extent of resection continues to be strongly associated with survival.

The effect of thermal therapy on the blood-brain barrier and blood-tumor barrier

The blood-brain and blood-tumor barriers represent highly specialized structures responsible for tight regulation of molecular transit into the central nervous system. Under normal circumstances, the relative impermeability of the blood-brain barrier (BBB) protects the brain from circulating toxins and contributes to a brain microenvironment necessary for optimal neuronal function. However, in the context of tumors and other diseases of central nervous system, the BBB and the more recently appreciated blood-tumor barrier (BTB) represent barriers that prevent effective drug delivery. Overcoming both barriers to optimize treatment of central nervous system diseases remains the subject of intense scientific investigation. Although many newer technologies have been developed to overcome these barriers, thermal therapy, which dates back to the 1890 s, has been known to disrupt the BBB since at least the early 1980s. Recently, as a result of several technological advances, laser interstitial thermal therapy (LITT), a method of delivering targeted thermal therapy, has gained widespread use as a surgical technique to ablate brain tumors. In addition, accumulating evidence indicates that laser ablation may also increase local BBB/BTB permeability after treatment. We herein review the structure and function of the BBB and BTB and the impact of thermal injury, including LITT, on barrier function.

Resting-State Functional Magnetic Resonance Imaging Networks as a Quantitative Metric for Impact of Neurosurgical Interventions

Objective: Resting-state functional MRI (rs-fMRI) has been used to evaluate brain network connectivity as a result of intracranial surgery but has not been used to compare different neurosurgical procedures. Laser interstitial thermal therapy (LITT) is an alternative to conventional craniotomy for the treatment of brain lesions such as tumors and epileptogenic foci. While LITT is thought of as minimally invasive, its effect on the functional organization of the brain is still under active investigation and its impact on network changes compared to conventional craniotomy has not yet been explored. We describe a novel computational method for quantifying and comparing the impact of two neurosurgical procedures on brain functional connectivity. Methods: We used a previously described seed-based correlation analysis to generate resting-state network (RSN) correlation matrices, and compared changes in correlation patterns within and across RSNs between LITT and conventional craniotomy for treatment of 24 patients with singular intracranial tumors at our institution between 2014 and 2017. Specifically, we analyzed the differences in patient-specific changes in the within-hemisphere correlation patterns of the contralesional hemisphere. Results: In a post-operative follow-up period up to 2 years within-hemisphere connectivity of the contralesional hemisphere after surgery was more highly correlated to the pre-operative state in LITT patients when compared to craniotomy patients (P = 0.0287). Moreover, 4 out of 11 individual RSNs demonstrated significantly higher degrees of correlation between pre-operative and post-operative network connectivity in patients who underwent LITT (all P < 0.05). Conclusion: Rs-fMRI may be used as a quantitative metric to determine the impact of different neurosurgical procedures on brain functional connectivity. Global and individual network connectivity in the contralesional hemisphere may be more highly preserved after LITT when compared to craniotomy for the treatment of brain tumors.

Characterization and expression of Megalobrama amblycephala toll-like receptor 22 involved in the response to Aeromonas hydrophila

The toll-like receptors (TLR) tlr22 was identified and characterized for the first time in one of the economically most important freshwater fish species in China, Megalobrama amblycephala. The full-length cDNA (4039 bp) of M. amblycephala tlr22 contains an open reading frame of 2706 bp, encoding a 901 amino-acid long polypeptide. The putative polypeptide contains 16 leucine-rich repeat (LRR) motifs, an LRR C-terminal, a transmembrane region and a cytoplasmic toll-interleukin-1 receptor (TIR) domain. Phylogenetic analyses revealed that M. amblycephala Tlr22 shared the closest relationship with a grass carp ortholog. tlr22 was constitutively expressed in nine tissues and during 10 developmental stages studied, albeit with varying expression levels. Along with many pathological changes observed after Aeromonas hydrophila bacterium infection, tlr22 and myd88 mRNA were significantly upregulated in blood, head kidney, spleen and intestine, indicating that tlr22 is involved in the immune response. These results provide an insight into tlr22 regulation mechanisms in the innate immune response to bacterial infection.

HDAC6: physiological function and its selective inhibitors for cancer treatment

Acetylation and deacetylation of histones are important in regulating gene expression and play a key role in modification of gene transcription. Specific HDACs isoforms can be regarded as a target for cancer therapy avoiding side-effects, HDAC6 with a unique physiological function and structure has become a hot issue recently. The unique isoform HDAC6 is involved in tumorigenesis, development and metastasis through tubulin, HSP90, invasin and ubiquitin-protein. Here we review the structure elements, biological function, and recent selective inhibitors of HDAC6, and study the structure-activity and structure-selectivity relationship.

Pial synangiosis for moyamoya syndrome in children with sickle cell anemia: a comprehensive review of reported cases

OBJECT

Pediatric patients with sickle cell anemia (SCA) carry a significant risk of developing moyamoya syndrome (MMS) and brain ischemia. The authors sought to review the safety and efficacy of pial synangiosis in the treatment of MMS in children with SCA by performing a comprehensive review of all previously reported cases in the literature.

METHODS

The authors retrospectively reviewed the clinical and radiographic records in 17 pediatric patients with SCA treated at the Morgan Stanley Children's Hospital of New York (MSCHONY) who developed radiological evidence of MMS and underwent pial synangiosis between 1996 and 2012. The authors then added any additional reported cases of pial synangiosis for this population in the literature for a combined analysis of clinical and radiographic outcomes.

RESULTS

The combined data consisted of 48 pial synangiosis procedures performed in 30 patients. Of these, 27 patients (90%) presented with seizure, stroke, or transient ischemic attack, whereas 3 (10%) were referred after transcranial Doppler screening. At the time of surgery, the median age was 12 years. Thirteen patients (43%) suffered an ischemic stroke while on chronic transfusion therapy. Long-term follow-up imaging (MR angiography or catheter angiography) at a mean of 25 months postoperatively was available in 39 (81%) treated hemispheres. In 34 (87%) of those hemispheres there were demonstrable collateral vessels on imaging. There were 4 neurological events in 1590 cumulative months of follow-up, or 1 event per 33 patient-years. In the patients in whom complete data were available (MSCHONY series, n = 17), the postoperative stroke rate was reduced more than 6-fold from the preoperative rate (p = 0.0003).

CONCLUSIONS

Pial synangiosis in patients with SCA, MMS, and brain ischemia appears to be a safe and effective treatment option. Transcranial Doppler and/or MRI screening in asymptomatic patients with SCA is recommended for the diagnosis of MMS.

The selection rule of graphene in a composite magnetic field

The generalized tight-binding model with exact diagonalization method is developed to calculate the optical properties of monolayer graphene in the presence of composite magnetic fields. The ratio of the uniform magnetic field and the modulated one accounts for a strong influence on the structure, number, intensity and frequency of absorption peaks, and thus the extra selection rules that are subsequently induced can be explained. When the modulated field increases, each symmetric peak, under a uniform magnetic field, splits into a pair of asymmetric peaks with lower intensities. The threshold absorption frequency exhibits an obvious evolution in terms of a redshift. These absorption peaks obey the same selection rule that is followed by Landau level transitions. Moreover, at a sufficiently strong modulation strength, the extra peaks in the absorption spectrum might arise from different selection rules.

Synthetic poly(ester amine) and poly(amido amine) nanoparticles for efficient DNA and siRNA delivery to human endothelial cells

Biodegradable poly(ester amine) (PEA)-based and poly(amido amine) (PAA)-based nanoparticles were developed for efficient in vitro siRNA delivery to human umbilical vein endothelial cells (HUVECs). They were screened, characterized, and compared with traditionally studied DNA-containing particles. Several of the polymeric nanoparticles tested were found to be effective for delivering functional siRNA to green fluorescent protein (GFP) + HUVECs, achieving 60%–75% GFP knockdown while maintaining high viability. While PEAs have been used previously to form polyplexes or nanoparticles for DNA delivery, highly effective siRNA delivery in hard-to-transfect human cell types has not been previously reported. PEAs and linear nondendrimeric PAAs were also found to be effective for DNA delivery to HUVECs using GFP-encoding plasmid DNA (up to 50%–60% transfection efficiency). PEAs and PAAs can be separated into groups that form polymeric nanoparticles effective for siRNA delivery, for DNA delivery, or for both.

Clinical and radiographic spectrum of septic pulmonary embolism

AIMS

To review the clinical presentation, radiographic findings, and outcome of therapy in children with septic pulmonary embolism.

METHODS

Retrospective analysis of patients in a tertiary paediatric facility in northern Taiwan.

RESULTS

Ten children were identified with septic pulmonary emboli in a four year retrospective chart review between 1998 and 2001. Seven were immunocompetent, two were premature infants, one had beta thalassemia major. Seven had community acquired staphylococcal infections and bacteraemia, of which six were methicillin resistant Staphylococus aureus (MRSA) isolates. Five had soft tissue infections, two bone infections, one suppurative otitis media, one catheter related infection, and one unknown foci of infection. Multiple and bilateral nodular pulmonary parenchymal lesions were common on plain chest radiographs, but chest computed tomography scans showed the additional findings of a "vessel sign" and central cavitations, confirming the existence of septic pulmonary embolism.

CONCLUSIONS

Community acquired MRSA infections occurred in seven patients with septic pulmonary embolism but without predisposing high risk factors. Critically ill children with skin, soft tissue, or bone infections, when associated with septic pulmonary embolism in an area with a high rate of MRSA, should be empirically treated with glycopeptides (such as vancomycin or teicoplanin) before susceptibility results are known, in order to minimise morbidity and avoid mortality.

Cultural value similarities and differences among Asian American ethnic groups

Using data on 570 Chinese, Filipino, Korean, and Japanese American college students from 3 previous studies (1 published [B. S. K. Kim, D. R. Atkinson, & P. H. Yang, 1999] and 2 unpublished [B. S. K. Kim, 1999; E. C. Wong, B. S. K. Kim, N. W. S. Zane, I. J. Kim, & J. S. Huang, 1999]), the authors subjected 22 items constituting 6 value dimensions of the Asian Values Scale (AVS; B. S. K. Kim et al., 1999) to the following structural equation modeling procedures: confirmatory factor analysis, factorial invariance analysis, and structured means analysis. The results of confirmatory factor analysis provided support for a hierarchical factor model when this model was compared with 2 competing models. The results of factorial invariance analysis indicated that the meanings of the factors within the hierarchical model were conceived similarly among the 4 Asian American ethnic groups. On the basis of these results, a structured means analysis was conducted, revealing similarities and differences between the ethnic groups' adherence to 6 cultural value dimensions. Implications regarding psychological services for these Asian Americans are discussed, and suggestions for future research are offered.

Design and development of the European American values scale for Asian Americans

Existing instruments for measuring Asian American acculturation emphasize behavior acculturation to the exclusion of value acculturation. Most are based on the assumption that acquisition of European American behavior occurs simultaneously with the loss of Asian behavior. With the advent of the Asian Values Scale (AVS; B.S.K. Kim, D.R. Atkinson, & P.H. Yang, 1999), it is now possible to assess adherence to Asian cultural values. This article describes the development of a scale that can be used to measure Asian American adherence to European American values. The current scale, combined with the AVS, can be used to independently measure Asian American acculturation to European American values and enculturation in Asian values.

Fluconazole therapy in neonatal candidemia

We reviewed 62 episodes (from 59 infants) of neonatal candidemia that occurred between January 1994 and June 1999. Except 5 term babies, all infants were premature (median gestational age [GA], 30 weeks) and birth weight was less than 2,500 g (median, 1,300 g). Most infants had reported risk factors and other neonatal problems. The age at onset of candidemia ranged from 15 to 173 days with a median of 34 days. In addition to catheter removal, all but one infants received antifungal agents and candidemia was eradicated subsequently in 46 episodes (75%). Eighteen infants with 19 episodes ever received fluconazole therapy. Fluconazole was administered as the first line agent in 6 episodes and successfully cleared candidemia in 5 episodes. Fluconazole was used as an alternative agent in an additional 13 episodes after amphotericin B (am B) +/- flucytosine were given for a period without a satisfactory result and eradication of candidemia was achieved in 8 episodes subsequently. All 18 infants tolerated fluconazole well and no withdrawal was required on account of its adverse effect. In contrast, am B alone was administered as the first line agent in 55 episodes and successfully cleared candidemia in 32 episodes (58%). This retrospective analysis suggests that fluconazole appears to be safe in neonates and can be used as an alternative agent in treating neonatal candidemia. A large-scaled prospective study may be needed.

Study of plasma endothelin-1 concentrations in Taiwanese neonates with respiratory distress

BACKGROUND

Endothelin-1 (ET-1) is a novel and potent endothelium-derived vasoconstriction peptide present in human plasma. In this study, plasma ET-1 concentrations were determined and their physiological significance was evaluated in Taiwanese neonates with respiratory distress.

METHODS

Sixty newborn infants consisting of 22 with respiratory distress syndrome (RDS), 13 with transient tachypnea of newborn (TTNB), 4 with meconium aspiration syndrome, 10 healthy preterm and 11 healthy full-term infants were included for plasma ET-1 determination. Plasma ET-1 levels were measured by enzyme immunoassay at the of age of 1 day. For those who were diagnosed with RDS, plasma ET-1 concentrations were scheduled for evaluation at the ages of 1, 2, 3, 7, 14, 28, and 35 days as long as oxygen was being used.

RESULTS

On the first day of life, there was no significant difference in plasma ET-1 concentrations between healthy preterm and term infants (3.92 +/- 0.88 vs. 3.56 +/- 1.98 pg/mL, p = 0.606). However, plasma ET-1 concentrations of infants with RDS were significantly higher than those with TTNB (6.46 +/- 0.58 vs. 3.77 +/- 1.29 pg/mL, p < 0.001). In RDS infants, plasma ET-1 concentrations showed no significant difference between those who developed bronchopulmonary dysplasia (BPD, N = 4) and those who recovered (non-BPD, n = 18) (7.84 +/- 1.85 vs. 5.81 +/- 2.76 pg/mL, p = 0.242).

CONCLUSION

Plasma ET-1 concentrations were similar in preterm and term infants. ET-1 concentrations were higher in infants with RDS than in infants with TTNB, which suggests that plasma ET-1 levels can be useful in the differential diagnosis. However, the plasma ET-1 concentrations can not be a predictor for BPD.

Persistent pulmonary hypertension of the newborn: experience in a single institution

Persistent pulmonary hypertension of the newborn (PPHN) remains one of the most challenging situations in the neonatal intensive care unit, and it is associated with high mortality and morbidity. The optimal treatment for PPHN is controversial. We report our 9-year experience in the management of PPHN through a retrospective review of 29 neonates with persistent pulmonary hypertension. The diagnosis of PPHN is made by echocardiography and/or preductal and postductal oxygen tension difference. The treatment modalities include supportive medical care, vasodilator therapy, mechanical ventilation and correction of underlying conditions. The wide diversity of etiologies of PPHN, the complications of vasodilator therapy, the management of assisted ventilation, the mortality and the morbidity are evaluated. There are 29 patients enrolled in this study, including 18 male and 11 female babies. Twenty-two patients (72%) are referred from other hospitals. The mean birth body weight is 2707 +/- 693 grams (range: 1450-4100 grams) and the mean gestational age is 37.1 +/- 3.1 weeks (range: 31-41 weeks). The underlying clinical conditions include meconium aspiration syndrome (n = 8), perinatal asphyxia (n = 7), respiratory distress syndrome (n = 5), sepsis and/or pneumonia (n = 4), congenital diaphragmatic hernia (n = 3) and idiopathic persistent fetal circulation (n = 2). In addition to supportive medical care and correction of underlying clinical conditions, most of the patients receive vasodilator therapy (Tolazoline) and nonhyperventilation respirator management. The overall mortality rate is 27.6% (8/29). The duration on ventilator therapy in the survival group (9.3 +/- 8.6 days) is not significantly different from in the mortality group (6.0 +/- 7.1 days) (p = 0.13). There is also no statistically significant difference between these two groups both in the maximal alveolar-arterial oxygen tension difference (594 +/- 53 mmHg and 613 +/- 37 mmHg, p = 0.145) and in the maximal oxygenation index (49.7 +/- 29.6 and 61.1 +/- 36.9, p = 0.172) before vasodilator therapy. However, twenty-four hours after treatment, these two parameters change significantly with the former changes to 426 +/- 198 mmHg and 643 +/- 7 mmHg, respectively (p < 0.001), and the latter changes to 21.6 +/- 15.8 and 82.3 +/- 54.8, respectively (p < 0.001). Skin rash, gastrointestinal hemorrhage, hypotension and hyponatremia are the most common complications of Tolazoline therapy. Eight patients have pulmonary complications including pneumothorax (n = 5) and pulmonary interstitial emphysema (n = 3). Two patients develop chronic lung disease. Three patients have neurodevelopmental handicap. In conclusion, we achieve a survival rate of nearly 75% in PPHN mainly with the administration of Tolazoline therapy and the nonhyperventilation respirator approach. Further well-controlled and multicenter studies with newer treatment modalities are crucial for the improvement of survival of PPHN in Taiwan.

Hirschsprung's disease presenting with diffuse intestinal pneumatosis in a neonate

In the neonate, pneumatosis intestinalis is almost always associated with necrotizing enterocolitis. The manifestation of diffuse intestinal pneumatosis in Hirschsprung's disease has been reported rarely. It may occur as a result of Hirschsprung's disease complicated with enterocolitis. We report a two-day-old female baby born at term with the problems of failure to pass meconium, progressive abdominal distension and bile stained vomiting. There was an early roentgenographic presentation of pneumatosis intestinalis which might have led to a diagnosis of necrotizing enterocolitis. However, the intestinal pneumatosis resolved within 48 hours. After anorectal manometry and contrast enema examination, an ileostomy was performed at the age of 23 days, and multiple biopsies of intestine showed aganglionosis up to the ileum at the level of 85 cm above the ileocecal valve. Unfortunately, the patient developed short bowel syndrome after operation and died suddenly after an accidental choking at the age of three months. This case suggests that Hirschsprung's disease may have an unusual early roentgenographic presentation with diffuse intestinal pneumatosis in the first few days of life. Anorectal manometries and suction biopsies are crucial for further diagnosis.

Treatment and outcome of congenital diaphragmatic hernia

BACKGROUND AND PURPOSE

Congenital diaphragmatic hernia (CDH) is a challenging condition and is associated with a high mortality rate; optimal therapy remains unclear. This retrospective study describes the clinical characteristics of treatment and outcome in 48 infants with CDH.

METHODS

Twenty-eight male (58%) and 20 female (42%) infants with CDH were treated from 1987 through 1998. The goals of the ventilator strategy were permissive hypercapnea (PaCO2 < or = 55 mm Hg) and avoidance of hyperventilation. Infants were initially ventilated with an intermittent mandatory rate of 40 to 60 per minute, peak inspiratory pressure of 20 to 25 cm H2O, and positive end-expiratory pressure of 5 cm H2O. High-frequency positive pressure ventilation was used if hypoxemia or severe hypercapnea (PaCO2 > 60 mm Hg) occurred. Most infants underwent repair after 3 days of age and only four infants underwent early repair within 24 hours of birth. A prophylactic chest tube was placed in the ipsilateral hemithorax postoperatively in all patients treated before 1996. The severity of respiratory distress was estimated by alveolar-arterial oxygen difference, oxygenation index, and alveolar-arterial ratio.

RESULTS

Forty-six patients presented with Bochdalek CDH, and two with Morgangni CDH. Antenatal diagnosis was made in 10 cases. Respiratory distress was the major manifestation and usually occurred immediately after birth. Six cases were diagnosed several months after birth and presented mainly with gastrointestinal symptoms. Eleven patients died before surgery and 37 patients underwent surgical repair. Two infants died postoperatively because of congestive heart failure and tension pneumothorax, respectively. The overall mortality rate was 27%. The major causes of mortality were severe respiratory failure, persistent pulmonary hypertension, pneumothorax, and associated anomalies.

CONCLUSION

Nearly 75% of patients in this series survived. This suggests that noninvasive respiratory care combined with delayed surgery may be an acceptable strategy for the treatment of CDH, and can be used in most medical institutions without equipment for extracorporeal membrane oxygenation therapy.

Diagnostic pitfalls in congenital right diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare disease of newborns. Right-sided diaphragmatic hernia is even rarer. The clinical and radiological presentations, which are well documented in left-sided diaphragmatic hernia, are variable in right-sided diaphragmatic hernia. This makes the diagnosis of right-sided diaphragmatic hernia more difficult. During a 12-year period, seven cases of right-sided diaphragmatic hernia were collected from a single institution. Their presentations and clinical courses have been reviewed. Low prenatal diagnostic rate, various roentgenogram expressions after birth, and absence of specific clinical presentations were noted. These expressions may become pitfalls in diagnosis and lead to inappropriate treatment. From our experience in these 7 cases and a brief literature review, we try to emphasize the characteristics and the diagnostic pitfalls of this disease. In conclusion, right-sided congenital diaphragmatic hernia has a variable clinical spectrum with high mortality and morbidity. Careful evaluation of the clinical presentations, ultrasonography and chest films is mandatory for precise diagnosis.

Candidaemia in special care nurseries: comparison of albicans and parapsilosis infection

OBJECTIVES

Candidaemia caused by Candida parapsilosis (CP) is being increasingly reported among infants in neonatal intensive care units (NICU). To assess relative severity, clinical manifestations of candidaemia caused by C. albicans (CA) and CP in a NICU were compared.

METHODS

Between January 1994 and July 1997, episodes of candidaemia occurring among infants hospitalized in the NICU were identified in a children's hospital. The demographic characteristics, associated risk factors, clinical manifestations and outcome of the infants with CP fungaemia were collected and compared with those of the infants with CA fungaemia.

RESULTS

Twenty-four episodes caused by CA and 22 episodes caused by CP were included in this study. No significant differences were found between the two groups for gestational age, birth weight, male gender, post-natal age at onset of candidaemia, frequency of antecedent neonatal events, prior duration of antibiotic therapy and hyperalimentation, as well as presence of central venous catheter (CVC). Infants with CA fungaemia were significantly more likely than those with CP fungaemia to present with hypoxaemia, bradycardia and respiratory distress requiring intubation, and have a longer prior duration of indwelling CVC and a higher dissemination rate. The eradication rate of candidaemia and overall case fatality rate were comparable in both groups. but CP fungaemia did not appear to cause acute lethal events.

CONCLUSION

The presenting signs of CP fungaemia are relatively not so severe, but CP fungaemia, which is relatively difficult to eradicate, increases the morbidity and mortality of the infants.

Vallecular cyst: an uncommon cause of stridor in newborn infants

Vallecular cyst, a rare but generally benign lesion in the larynx, may cause stridor and even life-threatening airway obstruction in early infancy. We retrospectively studied 14 cases of newborn infants with vallecular cyst. There was no gender predilection and most cases were full-term and appropriate for gestational age. The clinical presentations included stridor, chest wall retraction, feeding difficulties and failure to thrive. Laryngomalacia was the most common associated anomaly. Flexible laryngoscopy was sufficient for diagnosing the vallecular cyst and larygmalacia. Maintenance of airway patency, nutritional support, and de-roofing of the cyst were the mainstays of management.

CONCLUSION

Vallecular cyst should be included in the differential diagnosis of stridor in newborn infants. Respiratory and feeding difficulties in these patients can be dramatically improved after appropriate surgical removal of the cyst.

Neonatal necrotizing fasciitis: a report of three cases and review of the literature

OBJECTIVE

Necrotizing fasciitis (NF) is a predominantly adult disorder, with bacterial infection of the soft tissue. In children, it is relatively rare and has a fulminant course with a high mortality rate. In the neonate, most cases of NF are attributable to secondary infection of omphalitis, balanitis, mammitis, postoperative complications, and fetal monitoring. The objective of this communication is to report 3 cases of neonatal NF and provide a literature review of this disorder.

RESULTS

This review yielded 66 cases of neonatal NF. Only 3 cases were premature. There was no sex predilection and the condition rarely recurred. Several underlying conditions were identified that might have contributed to the development of neonatal NF. These included omphalitis in 47, mammitis in 5, balanitis in 4, fetal scalp monitoring in 2, necrotizing enterocolitis, immunodeficiency, bullous impetigo, and maternal mastitis in 1 patient each. The most common site of the initial involvement was the abdominal wall (n = 53), followed by the thorax (n = 7), back (n = 2), scalp (n = 2), and extremity (n = 2). The initial skin presentation ranged from minimal rash to erythema, edema, induration or cellulitis. The lesions subsequently spread rapidly. The overlying skin might later develop a violaceous discoloration, peau d'orange appearance, bullae, or necrosis. Crepitus was uncommon. Fever and tachycardia were frequent but not uniformly present. The leukocyte count of the peripheral blood was usually elevated with a shift to the left. Thrombocytopenia was noted in half of the cases. Hypocalcemia was rarely reported. Of the 53 wound cultures available for bacteriologic evaluation, 39 were polymicrobial, 13 were monomicrobial, and 1 was sterile. Blood culture was positive in only 20 cases (50%). Treatment modalities included the use of antibiotics, supportive care, surgical debridement, and drainage of the affected fascial planes. Two of the 6 cases who received hyperbaric oxygen therapy died. The overall mortality rate was 59% (39/66). In 12 cases, skin grafting was required because of poor granulation formation or large postoperative skin defects among the survivors.

CONCLUSION

Neonatal NF is an uncommon but often fatal bacterial infection of the skin, subcutaneous fat, superficial fascia, and deep fascia. It is characterized by marked tissue edema, rapid spread of inflammation, and signs of systemic toxicity. The wound cultures are predominantly polymicrobial and the location of initial involvement depends on the underlying etiologic factor. High index of suspicion, prompt aggressive surgery, appropriate antibiotics, and supportive care are the mainstays of management in the newborn infant with NF.

A survey on the treatment strategy of patent ductus arteriosus in very low-birth-weight infants

This study is a retrospective analysis of the clinical data of 67 very low birth weight infants (VLBWI) with symptomatic patent ductus arteriosus (PDA); all were admitted to four neonatal intensive care units (NICU) from January 1, 1996 through December 31, 1996. The mean gestational age was 27.9 +/- 2.4 weeks, the mean birth weight was 1078 +/- 193 g. Fifty-six infants (83.6%) had RDS, and 53 infants (79%) received artificial surfactant. The NICU at a regional hospital used CVD score > or =3 as the sole criteria and the remaining three NICUs used color Doppler echocardiogram to confirm a symptomatic PDA and to treat it; sometimes LA/AO > or = 1.3 was used as the criteria for indomethacin treatment. Two of these three hospitals sometimes used the pulsed Doppler echocardiogram as well as color Doppler examination as the treatment criteria. Seven infants (10.5%) had contraindication for indomethacin treatment; four of them closed after conservative treatment, and another three were subjected to surgical ligation. Of the remaining 60 infants, 3 were treated with oral indomethacin and 57 were treated with intravenous indomethacin. The mean age when initial treatment given was 3.8 +/- 1.5 days (range, 8 hours approximately 20 days). Among them 10 (16.7%) were within 24 hours after birth, 25 (41.7%) were between 24 and 48 hours, and 25 (41.7%) were beyond 48 hours. The dosage of indomethacin was 0.2 mg/kg per dose intravenously every 12 to 24 hours for three doses as a full course, if not contraindicated. The mean dose of indomethacin was 2.8 +/- 1.5; 10 infants (16.7%) received 1 dose, 15 (25%) received 2 doses, 27 (45%) received 3 doses, 3 (5%) received 4 doses and 5 (8.3%) received 6 doses. Among them, 51 infants (85%) PDA closed (including 2 treated with oral indomethacin), 9 (15%) failed to close and 6 of them received surgical ligation (including 1 treated with oral indomethacin). The complications associated with indomethacin treatment were hypoglycemia (52%), decreased urine output (42%) and gastrointestinal hemorrhage (32%). The infants with RDS had an earlier mean age of initial treatment than non-RDS infants (3.3 +/- 2.5 vs. 7.6 +/- 5.6 days; p < 0.05), and also had a higher closure rate (89% vs. 57%; p < 0.05). There was a closure rate of 85% in this multicenter retrospective analysis. Even though the infants received only one or two doses, they still had a good chance of ductal closure (21/25, 84%). To minimize the complications associated with indomethacin treatment in VLBWI, the protocol of indomethacin treatment should be re-evaluated.

Rickets of premature infants induced by calcium deficiency. A case report

Rickets of prematurity is not uncommon in neonatal intensive care units. Nutritional rickets in childhood is usually caused by vitamin D deficiency, but the rickets of prematurity is mainly attributable to calcium and phosphorus deficiencies. We present a premature infant with sequelae of necrotizing enterocolitis who needed prolonged administration of total parenteral nutrition (TPN), and who sustained ricketic fracture. After high calcium-fortified TPN supplementation the fracture healed well, and serum alkaline phosphatase dropped. This finding shows (1) serum calcium and phosphorus levels are of predictive value regarding rickets, (2) regular follow-ups of alkaline phosphatase levels combined with radiography in high-risk groups of premature infants are good tools for monitoring rickets, and (3) prolonged TPN administration needs to contain higher calcium and phosphorus concentrations in prematurity than in childhood.

Morbidity of survivors of neonatal respiratory distress syndrome under four years of age

This study evaluates the morbidity of neonatal respiratory distress syndrome (RDS) survivors in the Taiwan area. Sixty-three survivors of RDS, without surfactant therapy, were followed from January 1984 to December 1994. Comparisons between RDS survivors and 102 premature controls demonstrated that allergic rhinitis and hyperreactive airway (HRA) were adversely affected in RDS infants and children, especially in patients with chronic lung disease (CLD). It is interesting that a high incidence of otitis media and hypothyroidism was not found in this study, even though these have been reported elsewhere as more frequent among RDS survivors than among control subjects.

Neonatal meningococcal meningitis: report of two cases

Two neonates with meningococcal meningitis and meningococcemia are reported. The two, aged 28 and 16 days, respectively, presented similar symptoms of fever, poor appetite and poor activity. Both blood and cerebrospinal fluid cultures of each patient grew Neisseria meningitidis. The isolated bacteria were sensitive to penicillin, and both patients recovered completely after penicillin treatment for 22 and 15 days, respectively. In the antibiotic era, only 22 cases of neonatal meningococcal meningitis have been reported in the English literature. Among these reports, at least 7 patients survived without sequelae; 6 of those were treated with different combinations of antibiotics, including penicillin, for variable durations of 7-14 days. Therefore, effective antibiotic therapy for 14 days should be adequate in the treatment of uncomplicated neonatal meningococcal meningitis and meningococcemia.

Neonatal renal venous thrombosis--a case report describing serial sonographic changes

Neonatal renal venous thrombosis (NRVT) is a serious complication of newborns. Ultrasound is most useful in detecting NRVT. However, there is no detailed description of the evolution of ultrasound finding in NRVT. Here we report a patient with NRVT with complete ultrasound follow-up. Perivascular streaks were first seen at 3 days of age with a diffusely enlarged and echogenic right kidney. Echolucency then gradually appeared over the medulla area with shrinking renal size. Concomitant loss of renal function was evidenced by dimercaptosuccinic acid scan. The kidney became contracted at the age of 1 year. Since the pathognomonic perivascular streaks were present for only a few days, early ultrasound scanning should be performed for every newborn suspected of having NRVT.

Bacteremia due to non-typhi Salmonella: analysis of 64 cases and review

Within a 5-year period, 64 patients were hospitalized at the Chang Gung Memorial Hospital of Keelung (Taiwan) with bacteremia due to non-typhi Salmonella. Fifteen were < 24 weeks of age, 17 were between 6 months and 5 years of age, and 32 were > 18 years of age. An analysis of these patients revealed several significant differences between pediatric and adult patients. For instance, 87.5% of the adults but none of the children were debilitated because of severe underlying disease. Mortality was high (40.6%) among adults, but no deaths were observed among the children. Diarrhea occurred significantly more frequently among children (68.7%) than among adults (15.6%), while the contrary was observed in regard to chills, which occurred in 31% of adults and none of the children. It is concluded that bacteremia due to non-typhi Salmonella presents with different clinical features in adults than it does in children; furthermore, in adults the disease can be considered life-threatening, but in children it is associated with a favorable prognosis.

Pyogenic sacroiliitis in children: report of three cases

We report three children who were treated for pyogenic infection of the sacroiliac joint. The disease, usually present in late childhood or adolescence, is uncommon and difficult to assess so that the diagnosis is usually delayed. The three patients were two boys and one girl, aged 14, 15 and 12 years, respectively. A detailed history and physical examination are very important for establishment of the diagnosis. All the three cases presented with typical clinical triad of fever, limping gait and buttock pain. Pelvis compression maneuver, which directly stresses the sacroiliac joint, may aggravate the joint pain and suggest this diagnosis. On physical examination, this test is positive in all our cases. Nuclear scintigraphy is useful for localization of early lesions. For detecting abscess formation, magnetic resonance imaging was performed in two cases and computed tomography in one. In one of the patients, computed tomography failed to demonstrate an iliopsoas abscess formation, which was proved by magnetic resonance imaging later. Staphylococcus aureus was isolated from blood in all three patients. Prompt antibiotic therapy reduces complication and operation is rarely needed. With rapid and appropriate medical treatment, all our patients recovered without an sequelae.

[Cytomegalovirus infection in neonate--report of two cases]

The cytomegalovirus (CMV) is an abiquitous agent that infects almost all human beings at some time during their lives. In developing area of the world, 90% or more of the population is infected during childhood. However, in developed countries the infection is acquired at a lower rate. In neonates, CMV infection can be divided into congenital and perinatal infection. Congenital CMV infection is the result of transplacental transmission, CMV can be transmitted to the fetus following reactivation as well as primary infection during pregnancy. The incidence of congenital infection is 0.2% to 2.2%. Symptomatic congenital CMV infection is more likely to be the result of primary as opposed to reactive CMV infection during pregnancy. The clinical manifestations of symptomatic CMV infection are hepatosplenomegaly, microcephaly, jaundice, petechiae, small for gestation age, periventricular calcification and chorioretinitis. Mortality may be as high as 30% among the most severely affected infants. In the survivors, about 90% will develop mild to severe handicaps. Perinatal CMV infection can be acquired from exposure to virus in the maternal genital tract at delivery, breast milk, or through blood transfusion. In premature infants who require prolonged and intensive medical care, blood transfusions are an important iatrogenic cause of CMV infection. Transfusion-acquired perinatal CMV infection can cause significant morbidity and mortality, particularly in premature infants with a birth weight of less than 1250 gm born to CMV-seronegative mothers. So CMV acquisition can be prevented either by providing these infants blood products from seronegative donors or by using frozen deglycerolized red blood cells. Two cases of neonatal CMV infection are reported, one with congenital infection, the other with perinatal infection.

Effect of cross cylinder power on cylinder axis sensitivity

Astigmatic errors (0.50 D to 1.50 D in 0.25 D steps) were induced in each of 5 subjects, and cylinder axis thresholds were assessed from 12 reversals of a 2.5 degrees stepsize staircase for 0.50 D and 1.00 D cross cylinders (CC). Equivalent power thresholds were 0.077 D (0.05 SD) for the 0.50 D CC and 0.104 D (0.05 SD) for the 1.00 D CC. Findings are significantly different from predictions of a "linear" blur detection model, but are consistent with a model assuming constant blur thresholds and power-dependent distortion thresholds. Our results support the use of minimal CC power in refining cylinder axis.

Correlation of IR spectroscopic, heat capacity, diamagnetic susceptibility and enzymatic measurements on lysozyme powder

The interaction between protein and water is of fundamental importance for processes ranging from protein folding and enzymatic activity to anhydrobiosis. In this letter we bring together results from diverse types of measurements to give a unified picture of the hydration process for lysozyme. The data come principally from experiments with protein films and powders. The principal aim is to examine the relationship between the sites of water interaction, the extent of coverage, and the enzymatic activity, thus providing a better understanding of the relationship between water and enzyme dynamics.

Protein--water interactions. Heat capacity of the lysozyme--water system

Calorimetric measurements of the heat capacity of the lysozyme-water system have been carried out over the full range of system composition at 25 degrees C. The partial specific heat capacity of the protein in dilute solution is 1.483 +/- 0.009 J K-1 g-1. The heat capacity of the dry protein is 1.26 +/- 0.01 J K-1 g-1. The system heat capacity responds linearly to change in composition from dilute solution to 0.38 g of water per g of protein (h) and is an irregular function at lower water content. The break in the heat capacity function at 0.38 h defines the amount of water needed to develop the equilibrium solution properties of lysozyme as being 300 molecules of water/protein molecule, just sufficient for monolayer coverage. The heat capacity behavior at low water content describes three hydration regions. The most tightly bound water (0-0.07 h), probably principally bound to charged groups, is characterized by a partial specific heat capacity of 2.3 J K-1 g-1, a value close to that for ice. A heat of reaction associated with proton redistribution is reflected in the heat capacity function for the low-hydration region. Between 0.07 and 0.25 h the heat capacity increases strongly, which is understood to reflect the growth of patches of water covering polar and adjacent nonpolar portions of the protein surface. The hydration shell is completed by condensation of solvent over the weak-interacting portions of the surface, in a process displaying a transition heat.