Short communication: Reducing agents attenuate methylglyoxal-based browning in Parmesan cheese.

The microbial production of methylglyoxal in cheese has been linked to the formation of brown pigmentation and distinctive volatiles. This study investigated methods for preventing methylglyoxal-induced browning in Parmesan cheese through the addition of reducing agents. Cheeses were treated with the reducing agents sodium bisulfite, glutathione, and erythorbate at 2:1 and 4:1 molar ratios with added methylglyoxal, and then incubated at 10 °C. Colorimetric methods were used to determine degree of browning at 0, 3, and 6 d. Sodium bisulfite and glutathione inhibited the browning reactions of methylglyoxal compared with the control. Erythorbate was much less effective than the other compounds at inhibiting browning, yet was significantly less browned than the control. These reducing agents are thought to act as strong nucleophiles that can form thiohemiketals and thioketals at the carbonyl carbons of methylglyoxal.

Short communication: Evidence for methylglyoxal-mediated browning of Parmesan cheese during low temperature storage.

Brown pigmentation can occasionally form in Parmesan cheese during the ripening process, creating an unappealing appearance and associated off-flavors. The browning reactions proceed at refrigerated temperatures and in the relative absence of reducing sugar, contrary to typical Maillard browning. Residual sugars, lipid oxidation products, byproducts of fermentation, and (or) enzymes may react with primary amines in cheese to form brown pigmentation and concomitantly generate volatile compounds unique to each of these reactions. Determining the volatile profiles provides a means of understanding the potential substrates involved and causative reaction pathways. This work is divided into 2 segments. The first portion characterized the pigmentation and the browning index of Parmesan cheeses with and without extensive browning. The second phase examined the volatile character of the cheeses using gas chromatography-mass spectrometry. Various pyrazines, such as 2,3,5-trimethylpyrazine and 3,5-diethyl-2-methylpyrazine, were found in the brown cheeses but were not present in the white samples. The formation of pyrazines is proposed to result from the spontaneous condensation of aminoacetone. Aminoacetone can be formed by the Strecker degradation of amino acids with methylglyoxal, the latter a byproduct of sugar fermentation. Evidence is provided to support a browning pathway mediated by the production of methylglyoxal in Parmesan cheese.

Nitrous oxide cryotherapy for intraepithelial epithelioma of the conjunctiva.

Nine patients were treated with the nitrous oxide eyelid cryoprobe for large or recurrent intraepithelial epithelioma of the conjunctiva or cornea. Nitrous oxide cryotherapy is more convenient for ocular cryosurgery than liquid nitrogen therapy and seems to be as effective for intraepithelial epithelioma. Surgical debulking of the lesion is recommended before cryosurgery. An obvious advantage of cryosurgery over surgical modalities for intraepithelial epithelioma is that large areas of tumor as well as surrounding tissues can be treated. This procedure results in a higher cure rate and avoids grafting and symblepharon formation. The complications of light cryosurgery seem to be minor even when the cornea is treated. Heavy cryosurgery may result in severe iritis, posterior synechiae, and corneal scarring. A biopsy-proved diagnosis of intraepithelial epithelioma can be misleading and does not rule out the presence of underlying malignant disease.

Bilateral congenital lacrimal sac mucoceles with nasal extension and drainage.

A newborn infant with bilateral mucoceles of the lacrimal sacs also had submucosal masses along the floor of the nose beneath the inferior turbinates communicating with the mucoceles. Drainage of the mucoceles was performed by needle aspiration and wide marsupialization of the nasal masses into the nose under direct visualization. To our knowledge, this is the first time that intranasal extension of mucoceles has been reported, and the first time that lacrimal sac mucoceles have been successfully treated via direct nasal drainage. We advocate careful nasal evaluation in cases of congenital lacrimal sac mucoceles to determine whether intranasal extension is common and whether intranasal drainage can be curative.

Metastatic small cell carcinoma masquerading as orbital myositis.

A case of discrete metastases to an extraocular muscle from a silent small cell carcinoma is described. Clinically, diagnostically, and pathologically this masqueraded as orbital myositis. It was not until a full thickness muscle biopsy was obtained that the diagnosis was realized. The need for deep biopsy is stressed. Discrete metastases to an extraocular muscle without other orbital soft tissue involvement is rarely reported. This is the first reported case from a small cell primary tumor. Metastatic orbital disease is discussed.

Metastatic carcinoid unresponsive to radiation therapy presenting as a lacrimal fossa mass.

A case of metastatic carcinoid tumor presenting as a lacrimal fossa mass is described. This appears to be only the fourth case report of metastatic carcinoid to the orbit and the first to include ultrasound evaluation. the tumor mass did not regress despite radiation therapy as documented on serial ultrasound examinations. Therapeutic implications of this finding are discussed. Metastatic carcinoid tumors are reviewed.

Techniques in eyelid wound closure.

While one of the most basic techniques in eyelid surgery is the repair of an eyelid defect that involves the margin, many eyelid defects are still poorly repaired; and much confusion still exists in this area. Based upon sound anatomic and surgical principles, we suggest several modifications of classically described techniques: (1) The greyline suture is replaced by a tarsal suture through the meibomian gland orifices to provide a stronger closure and better alignment. (2) All tension of closure is supported by the deep tarsal sutures rather than by the margin sutures to avoid notch formation or unsightly scars. (3) A two-layered closure where orbicularis and tarsus is closed in a single layer is technically easier and gives results comparable to the classically taught three-layered closure. Conjunctival sutures in the tarsal portion of the eyelid are unnecessary and frequently cause corneal irritation. (4) When lid resection is performed, a pentagonal excision rather than a "V" or wedge resection should be used to minimize tension on the margin when closed. We present in an illustrated step-by-step fashion our preferred technique which gives consistently good results.