Kinetics of the photosubstitution of cis-bis(benzonitrile)dichloroplatinum(II) in chloroform

Under 254 nm irradiation cis-[Pt(C6H5CN)2Cl2] is converted to H2PtCl6. Absorption of light by both the metal complex and the solvent contribute to the first step of this process, suggested to form HPt(C6H5CN) Cl3. A linear dependence of the reaction rate on light intensity appears to rule out chlorination by trichloromethyl radicals. However, at higher light intensities a higher order dependence on intensity develops, and under 313 nm irradiation is dominant, and a reaction between trichloromethyl radical and the excited state complex is proposed to account for this

A perpetual switching system in pulmonary capillaries

Of the 300 billion capillaries in the human lung, a small fraction meet normal oxygen requirements at rest, with the remainder forming a large reserve. The maximum oxygen demands of the acute stress response require that the reserve capillaries are rapidly recruited. To remain primed for emergencies, the normal cardiac output must be parceled throughout the capillary bed to maintain low opening pressures. The flow-distributing system requires complex switching. Because the pulmonary microcirculation contains contractile machinery, one hypothesis posits an active switching system. The opposing hypothesis is based on passive switching that requires no regulation. Both hypotheses were tested ex vivo in canine lung lobes. The lobes were perfused first with autologous blood, and capillary switching patterns were recorded by videomicroscopy. Next, the vasculature of the lobes was saline flushed, fixed by glutaraldehyde perfusion, flushed again, and then reperfused with the original, unfixed blood. Flow patterns through the same capillaries were recorded again. The 16-min-long videos were divided into 4-s increments. Each capillary segment was recorded as being perfused if at least one red blood cell crossed the entire segment. Otherwise it was recorded as unperfused. These binary measurements were made manually for each segment during every 4 s throughout the 16-min recordings of the fresh and fixed capillaries (>60,000 measurements). Unexpectedly, the switching patterns did not change after fixation. We conclude that the pulmonary capillaries can remain primed for emergencies without requiring regulation: no detectors, no feedback loops, and no effectors-a rare system in biology. NEW & NOTEWORTHY The fluctuating flow patterns of red blood cells within the pulmonary capillary networks have been assumed to be actively controlled within the pulmonary microcirculation. Here we show that the capillary flow switching patterns in the same network are the same whether the lungs are fresh or fixed. This unexpected observation can be successfully explained by a new model of pulmonary capillary flow based on chaos theory and fractal mathematics

Kinetics of the photolysis of bis(triethylphosphine)dichloroplatinum(II) in chloroform

Under 254 nm irradiation [Pt(Et3P)2Cl2] in chloroform is converted to H2PtCl6. Absorption of light by both the metal complex and the solvent contributes to the first of this process, suggested to form HPt(Et3P)Cl3. The rate law for the reaction can be expressed as afR + bfRfSt, bfRfst, where fR and fs represent the fraction of light absorbed by the metal complex and the solvent, respectively, and t is the elapsed time. The direct dependence of the rate on the time of reaction was proposed to arise from an increasing concentration of HCl, which can react with the excited state metal complex to yield HPt(Et3P)Cl3

The novel use of a pedicled submental flap in the treatment of recurrent fourth branchial cleft anomalies in the pediatric population

OBJECTIVES: Fourth branchial cleft anomalies are rare and can present in a variety of ways in the head and neck. Limited data exists on the treatment of complex recurrent fistulas. We present a unique case utilizing a pedicled submental flap in the management of a persistent fourth branchial anomaly and discuss the use of pedicled flaps in the pediatric population. Study Design: Retrospective chart review. Methods: Patient data were collected from a tertiary care pediatric hospital medical record. Results: An 8 year old patient presented to our institution with a history of recurrent left neck infections and multiple failed incision and drainage procedures. Aggressive surgical options failed. She eventually underwent a complete resection of the fistula with partial pharyngectomy, left selective neck dissection, and two layered closure of the pharyngotomy defect with an oversewn pedicled submental island flap. The surgery was uneventful and the patient is without evidence of recurrence 7 months postoperatively. Conclusions: Treatment options for fourth branchial anomalies include incision and drainage, endoscopic cauterization via direct laryngoscopy or open neck surgery with complete sinus tract excision and thyroidectomy. Persistent disease requires aggressive management with partial pharyngectomy with/without the use of additional soft tissue for coverage. For significant pharyngeal defects, submental pedicled flaps can be utilized in repair and closure. To our knowledge this is the first reported case of a pedicled submental flap for closure of a pharyngotomy defect in the pediatric population. The use of the submental flap in this group is feasible, with few to no complications, and offers very acceptable cosmesis

Unexpected pathologies in pediatric parotid lesions: Management paradigms revisited

Objectives: To present case vignettes of unusual pediatric parotid pathologies and discuss management paradigms in the context of these lesions. Study design: Retrospective case series. Setting: Free-standing, academic tertiary care pediatric hospital. Methods: All patients over the past 18 months undergoing parotidectomy for a parotid mass were reviewed (N= 5). Results: Ages ranged from 17 months to 16 years. All presented with a remarkably similar clinical course, consisting of a persistent parotid mass for more than 3 months which was usually painless. Most (4/5 patients) had been treated with antibiotics prior to Otolaryngology consultation. Fine-needle aspiration (FNA) was performed on 3 patients and was diagnostic in one. Complete excision of the mass was performed in each child through a parotidectomy approach (3 total, 2 lateral lobe). The final pathology showed metastatic neuroblastoma (17 months old), undifferentiated primitive sarcoma (22 months old), mucoepidermoid carcinoma (11 years old), nodular fasciitis (12 years old), and hyperplastic lymph node (16 years old). The patient with neuroblastoma died from complications of bone marrow transplant. Conclusions: The differential diagnosis for a persistent pediatric parotid mass is expansive and differs from that found in the adult population. As this series highlights, in many cases, it is impossible to discern the pathology, or rule out malignancy, based upon the clinical course, imaging, or FNA results. Surgical excision remains the standard for management of these patients and is both diagnostic and therapeutic. Our anecdotal case series highlights the importance of having a low threshold for parotidectomy in these children. © 2011 Elsevier Ireland Ltd

Unexpected pathologies in pediatric parotid lesions: Management paradigms revisited

Educational Objective: At the conclusion of this presentation, the participants should be able to discuss the management of persistent pediatric parotid masses and explain the role of surgery as a diagnostic and therapeutic tool for these lesions. Objectives: To present case vignettes of unusual parotid pathologies and discuss management paradigms in the context of these lesions. Study Design: Retrospective case series. Methods: Five consecutive patients over the past 18 months undergoing parotidectomy for a parotid neoplasm, each with an unusual pathology, were reviewed. Results: Ages ranged from 17 months to 16 years. All presented with a remarkably similar clinical course, consisting of a mostly painless, persistent parotid mass for more than 3 months. Most (4/5 patients) had been treated with antibiotics prior to otolaryngology consultation. Fine needle aspiration (FNA) was performed on 3 patients and was diagnostic in one. Complete excision was performed in each child through a parotidectomy approach (3 total, 2 lateral lobe). The final pathology consisted of metastatic neuroblastoma (17 mos. old), undifferentiated primitive sarcoma (22 mos. old), mucoepidermoid carcinoma (11 years old), nodular fasciitis (12 years old), and hyperplastic lymph node (16 years old). The patient with neuroblastoma died. Conclusions: The differential diagnosis for a persistent pediatric parotid mass is expansive. In most cases it is impossible to discern the pathology, or rule out malignancy, based upon the clinical course, imaging, or FNA results. Excisional surgical management remains the gold standard diagnostic and therapeutic tool for most patients. Our anecdotal case series highlights the importance of having a low threshold for parotidectomy in these children. Copyright © 2010 The American Laryngological, Rhinological, and Otological Society, Inc